Pick any story-based game series and there's a good chance that you'll find the following:
1) The lead character will start off with amnesia (and/or find themselves in an unfamiliar location) and have to "earn" their skills as the story progresses
2) The sequel will either strip the lead character of their powers or put the player in the shoes of a new, unskilled character
Some games even do this in a single title - Darksiders is a prime example, as after a few glorious minutes of stopping around with War's maxed-out powers, you're then stripped of everything and sent out to reclaim them all, in a strange new post-apocalyptic world...
The reasons for this are perfectly understandable from the developer's point of view:
- New players aren't overwhelmed by too much complexity
- It provides convenient hooks to base the gameplay, reward structure and story around
- It reduces the risk of players getting bored of the game's mechanics
To be fair, these are pretty good reasons. However, this sort of setup greatly increases the frustration for existing, experienced players: if you've played the original game (or anything similar), then you're basically reinventing the wheel. Again and again and again.
Worse, depending on how long it takes to unlock everything, it can lead to confusion or frustration while playing the main game, as players find themselves confronted with bonus items or zones they can't get to, no matter what they try - and this can be especially frustrating when the game doesn't provide any hints as to what abilities are waiting to be unlocked or when this will happen.
And that's where I am now. For instance, I'm looking forward to Batman: Arkham City, but the original drip-fed you new abilities right up until the penultimate chapter. If the sequel reuses this formula, it could end up being a long and frustrating slog! Similar applies to unlocking access to better cars and weapons in the GTA series, running through weapons training in Call of Duty, being taught how to look around the screen in Halo and several dozen more besides...
Admittedly, there isn't an easy solution for developers: make the tutorials too short and new players will struggle. Allow players to skip the initial sequences and they'll miss out on a significant chunk of the game's story setup - and it's inevitable that some new players will decide to skip the tutorials and get stuck, resulting in negative commentary on t'interwebs.
With that said, there are several potential ways around this. The simplest approach is to keep the tutorials separate from the game and allow players to skip this if they can pass a set of short challenges, thereby proving their skill and experience. A second approach is to simply layer new abilities on top of the old abilities (a common Shonen manga trope). A third approach would be to map out multiple paths through the game's story, depending on the skill demonstrated by the player.
All of these have their good and bad points, ranging from impact to the story to the need for additional content (and associated playtesting). However, they're also ways to keep experienced players interested...