In the current state, underwater combat isn't exactly fun for anyone and has a lot of problems regarding perspective and physics underwater. Most importantly not being able to use your skills underwater makes the underwater fractal feel like a drag and locks you out of certain playstyles completely. Currently, Renegade is basically locked into using Mallyx and Jalis (due to providing boonstrip and stability) and can't even take Kalla or Ventari underwater. What's more, is that the possible instabilities (according to Guild Wars 2 Wiki on November 7th, 2019) are as follows:
This means that you have a 33 % chance of having No Pain, No Gain in the fractal, which forces your Renegade on Mallyx in meta compositions. Not to mention the fact, that there is a high chance of getting a more meaningful and subjectively annoying instability instead of getting an instability that's a laughable joke at its best.
My suggestions for fixing the underwater content, making it easier for people without actually proper groups and fractal knowledge and making it more proactive and less of a hassle in terms of compositions and traits are these:
1. Increase the number of possible instabilities in the underwater fractal to make sure that you are not always met with a No Pain, No Gain, Afflicted and Vengeance combo.
2. Make all/most of the skills available underwater! There is no reason you should be punished for playing a profession that harshly. This would also do some damage control regarding the fact that some professions lack proper underwater weapon skills.
(3. Re-think underwater combat as a whole and make it more enticing and make underwater gear more attainable. As of now, getting proper underwater gear is a hassle and there is not really a good reason for it to be so much harder to come by than your regular gear if you want to include underwater content in the late game game modes.)