Of course, it shouldn't be done by a single people however they want, rather have an international group of experts deciding how things should be done, and not do so until it has been tested to be safe. But gene manipulation technology isn't even close for making that possible. Yet.

If it was scientifically sound to where there wasn't a great risk of dying then hell yes I would like some fire from my fingertips...nature be damned

Problem is people wouldn't be able to handle that kind of power and the world would be torn apart in no time.

I dislike the idea because it strikes me as a cop-out for weak willed people who don't want to face all the challenges of life that a normal person would have. Example, you're fat, so you do something to yourself that will make you... not fat. I personally don't think it would feel very satisfying to deal with physical problems that can be fixed by yourself over time by basically entering a "make me like this" cheatcode. And making superficial changes to yourself because you don't like how you look would be even worse.

If this were to exist, the public should only be able to use it if they're deemed qualified to. As in, you can't make trivial changes to yourself, like running speed just because you want it NOW and don't feel like working out. But things like... I don't know, maybe you have stunted limb growth, and this has a chance of fixing that problem. Things like that would be fine.