I always found it weird that heavy armor stops some spells as easily as a sword. And that everything is just a clear cut hit or miss.
I also feel that DND has lost a bit of creativity when it comes to class creation. We still have the same basic stuff from 20 years ago. Lots of people want to play other variations that don't come to life when you have to take certain class and skills just to get a taste of what you are actually after.