I've been planning and tweaking my future 1000 point list for about a month now. I have it to the point where I'm comfortable enough to debut it but one thing that it lacks really bothers me. No melta bombs. I tried to work them in for my Justicars but to do so would require other changes that I didn't like. Without things like power fists and melta guns I'm thinking mb's might be important. Is it meh, wise idea or a must for these things in a pure GK army?

Well my 1000 pts has no meltas but I would say give them a try and see how you deal with it and afterwards think would having meltas or anything have helped in anyway. Sometimes only way is to have a test run.

I've found them useful on a FAGK Justicar as after DS they're closer to Enemy Vehicles, so there's a greater chance of using them. However, not many people DS nowadays so....
I would say that if you have 5 points left when making a list then get them, but only after getting Frags first if you haven't already taken them.

5 points to give you a chance of not getting a squad bogged down with an enemy Dreadnought for the entire game? Yes Please.