So, you want just to sit and watch everybody else fighting? And I thought HL was supposed to be a game. A game with a story, which you should follow even if you don't know what to do next. For that, you need other characters yelling at you.
Yes. I was playing sniper and some stupid say was running towards me and cloaking, he didn't change his direction, so it was an easy headshot, but I was called a hacker. Come on, shooting an invisible spy is even an achievment!
Losing the gravity gun would mean losing the ability to use the world around you. It would turn all objects around you into useless decoration. Also I think that the gravity gun became the trademark weapon for HL2 and its episodes, so... no, don't lose it.