I personally think underwater combat is a very neat aspect of Guild Wars 2. However, it needs to be greatly improved and there are a lot of problems with it. I have recently heard a rumor that it is going to be phased out and I really hope not, because I think many of the underwater areas are well done and intriguing.
Reasons to keep underwater combat:
1. There is a lot of content underwater and in areas only accessible by swimming (islands). If underwater combat were removed, the underwater areas would become very boring, because there would be very little to do there. And removing swimming altogether would make these areas inaccessible.
2. Underwater combat is an improvement over only land combat in Guild Wars 1.
Things wrong with underwater combat:
1. About half of the skills and even some traits don’t work underwater.
2. Very few weapons to choose from for underwater combat.
3. Getting a good quality breather (above masterwork) is very difficult to say the least. And even the masterwork level 80 breather only has one type of stats (no variety to choose from).
Reasons why players probably don’t like underwater combat:
1. Players feel weaker underwater than on land. This is because of the lower quality breathers, the fact that they are limited to certain skills that may not work well with their build, and the fact that some of their traits suddenly don’t work when they go underwater (or merely become pointless because the skills they reference are not usable underwater).
2. Players feel constrained by a smaller variety of good builds for underwater combat. This is because of the lack of usable skills and traits for underwater combat and the fact that each class only has one or two weapons for underwater combat.
Suggestions for fixing underwater combat:
1. Add more breathers of all qualities (common, fine, masterwork, rare, and exotic [and make them as easily accessible as any other kind of equipment]; make ascended breathers accessible to people other than fractal enthusiasts).
2. Make more skills available for underwater combat and maybe even add a few for underwater combat only.
3. Add more weapons for use in underwater combat (including one-hand and off-hand weapons).
4. Incorporate underwater combat more into traits.