I'd like to be able to mutate better. Namely:
- i'd like to retain ability to use jet skis after mutation, seeing there are muties riding 'em in abandoned water facility just fine;
- i'd like to remain able to use psi abilities, provided i was able to prior to mutation, seeing there is a strong mutant able to use 'em in the game;
- i'd like to remain able to use crafting skills, provided i had some prior to mutation, seeing Booth who does just fine doing fine hand work - tatooes;
- i'd like to remain able to use grenades and other throwables, provided i had some Throwing skill prior to mutation.
And i'd love to be able to choose between various types of mutation, by injecting certain mutagen sequences into mutagen tanks in Deep Caverns and then mutating there into something different than "default" D5 mutagen produces. In particular, i'd love to see mutations which do not force player character to always wear claws for weapons, and mutations which produce body armor with various armor penalty and defenses - some as low as 30% armor penalty, others close to 90%. There are certain feats impossible to use or becoming inefficient when it's one and the same 50% body armor after mutation.
Seeing how it's still possible to be stealthy, and even develop Agility to 7+ hard points while mutated, hence also getting (or even retaining) Interloper feat and its specialization if any, we can reach lots of places in the game where it'd normally be impossible to fight into, like Your House in Core City with its crafting benches. Seeing how it's still possible to use the Juice and travel through Rifts after mutation as well, even more places could be reached. But being unable to do things listed above totally ruins lots of possible gameplay after mutation - which could be whole new "chapter" of the game, when we go to all the various places (not just the most like we can now) and fight or sneak our way into areas which previously were always non-hostile, and/or simply doing it in this new - mutant - form with its mighty different (to any regular build) abilities and features.