This will be an unpopular opinion - which I totally understand - but I kind of like the way things are now in terms of player development and retirement.
Currently player development is all over the place. I have a 22 year old that has only improved 1 rating (+1 shooting) in two seasons with no additional improvement in sight. I also have a handful of 22-27 year olds that have improved almost every single rating over the first two seasons. Also a 34 year old that has improved skating, spirit, endurance and +1 overall this season. That all being said, I like the slower rates of improvement as it doesn't allow teams to stack up with younger players and end up with all 90+ players in a few seasons (like the old game worlds). The truth is most 22-27 year olds, on average, will still improve +1 "overall" every 2 seasons (i.e. if you sign a 22 year old 88 overall, when they are 26 they will be 90 overall). Obviously there are exceptions to this, certain players improve faster, slower or not at all - which is where scouting becomes important. I suppose it's less exciting to see those development messages in your inbox less frequently, but I'd rather that than GHL teams with all 90 rated players. The way things are now also values older veteran type players, which is how it should be.
As for early retirement - age 23 is a bit excessive. I can agree with that. But I personally think the game is more fun when the occasional curve ball is thrown your way and you have to react... and manage. Key word being occasional. If we start seeing 23 year olds retiring every year, then it should probably be changed. Then again, if it's "lazy" players that retire early, then this adds a ton of strategy to the game when signing players and I'm all for more strategy.
Just want to avoid the game becoming "who can obtain the youngest team possible and keeping that team in tact for the next 10 seasons without any bumps in the road". Because that was the case in the old world and the same teams won over and over again without much change year over year.