If you haven't realised, it's probably time that you do: Software across the years are getting more and more restrictive. Apple started it all with their iOS platforms. You can't do what you like with them. Instead, they will dictate what you can do with these devices, like it or not. I have no idea if the Mac OSes are the same, but I know Windows is somewhat edging towards that direction (whether it's intentional or not I don't know. I hope it isn't).
There are arguments for this, on the user side that is, in support of this iron fist control. Most people wouldn't want to be messing with the internals of their device (phone, tablet, full-fledged PC), accidentally. That's understandable. But it doesn't mean they have to lock away everything and not give out the key at all.
I'd say, if you don't know what you're doing, yet you still do so, get your device in trouble, and were not prepared to accept the consequences, then you're a dumbass, and I couldn't care less for you (I do care for your poor device though). As a developer, you can hide the full access away, and warn people if they might do something that could break their device (Mozilla does that nicely, with warning messages and stuff) but still give full access fairly easily for those who know how to get it.
Anyway, WHY am I talking about all this? I am a strong advocate of jailbreaking, rooting, etc, and retaining full control over your devices. Stuff that you PAID FOR with your hard-earned money. "Why do I need to do that?" you might ask, "The device performs what I want it to already." See, that's for most of the time... MOST. I'm going to concentrate on iOS devices hereon, since those are the most restrictive (almost claustrophobic device).
So, you buy an iPhone, or an iPad, and you go about your daily use of playing games and communicating, surfing the web and social networks. You make a few app purchases... and then due to region restrictions, you can't download some stuff which you'd like to play. That's the first frustration. There are ways around it, and usually the people who experience this are 1. Multilingual, 2. Well-exposed to other countries and culture. So basically, if you're the above-average person, with a good taste for stuff from all over the world, you'll run into this problem sooner or later.
Then after maybe a few years, you want to download that game you purchased from some time ago, for some reason: perhaps to play it again for nostalgia, or maybe your friends finally picked it up, or maybe it suddenly became cool, or it could even be an app that you realise you need it again for whatever function it served. You try to redownload it... only to discover it's been swiped off your list of purchases, and no longer available to you. What are you going to do now? You PAID for it previously. They have just taken it away from you. There's also nothing stopping them from taking away anything or everything else btw. (And this is what happened to one of my games which I had paid for. True story. I am not telling you of a hypothetical scenario.)
Another few years later, you want to migrate from your old device to a new one (or maybe just 2 years after you purchased your old device!) and you want to move some of your game DATA over. There is only one legacy way: Save a full back-up of your device, and do a restore to the new device. It should work. SHOULD. If there's some incompatibility, or the restore fails for some reason (trust me, it can and will happen), you're stuck.
Unfortunately, companies like Apple can't give a damn how many hours you took to grind the level of that character up on your device, or how elegant your solution to that level 27 problem is, and there's no other way to migrate game data over for games that don't have some form of cloud or online sync service. You're dead. You can kiss that save-game goodbye.
Don't forget, you can't do partial migrations, or other nifty things like backing up your highscores while getting rid of the game to make space for new games (and then restoring your highscore to the old game some time in the future if you want to play it again).
So, if you don't mind getting swindled, stolen from, have your save-games gone, being told exactly what you can do with your device, then I guess this post is not relevant. Otherwise, you might want to take some proactive measures to prevent all these problems from occuring.
1. Jailbreak, Root, (or equivalent) your device. If you can't (e.g. iOS 9 does not have a jailbreak), consider NOT GETTING the device. Otherwise, you have to accept that, for at least a period of time until a solution can be found, you're at the mercy of the company to do whatever they want with your device. (Doesn't sound very appealing for a device you've paid a couple of hundred bucks for right? You don't really get to own the device...)
2. Get 3rd party software to help manage your device (iFunBox seems to be pretty good all these years for helping you manage your full access to iOS devices) after you've gotten full access. This way, you can do whatever you need to with your device.
3. Backup. This is not the shoddy backup that Apple has. You want to be able to function WITHOUT INTERNET. So, back up the App installation files themselves. iTunes may not allow you to install certain stuff that they feel like not allowing (like regional restriction change, etc. You really don't know what they'll do). Backup your data from the app. Literally copy the whole app as it is installed in your device. This way, after installing a fresh app on the new device, browse to the folder, paste your complete data in that place, and you'll have your app exactly as it was. As good as a snapshot frozen in time.
4. Never update anything unless you know what the update brings. Updates may bring functionality or restrictions. Sometimes both. Sometimes updates just break everything (remember the fail of Apple Maps?). You have to know what you're getting. Weigh your options carefully. Let others be the guinea pigs to update. There'll always be people who are willing to risk it, who can risk it, and then there are the dumbasses who don't know what they're doing. Let them suffer the problems first.
And don't forget that iOS updates will jail the devices again.