I'm againts the current form of death streaks. Even if I died a lot just to get a single kill in somewhere like Quake, I don't want the game to help by increasing health etc. It doesn't feel as fun as finally nailing the players without any help. Not to mention, it can get annoying for those players who are a lot better and they get killed only due to the death streaks, which can feel "cheap".
If I wanted death streaks to be included to the game, I wouldn't do it the same way Crysis 2&3 do it (or any other game, they always seem to do it the "cheap" way). Instead of increasing health etc. I would increase the amount of information the player receives. Move more during combat, look for movement in water and shadows, don't be too far away from teammates, use power jumps during combat etc. This way the game would still force the player to be good, but the players would learn what they do wrong.
I think the above idea isn't really a death streak bonus but I would rather have that in a game where I'm horrible than a death streak bonus, which allows me to cause nuclear explosions when I'm dead or increased health.
Edit: Just remembered Warhammer 40,000 Space Marine where players could copy enemies' classes after they died. That's a good idea for a death streak bonus. No "cheap" modifiers and the player still needs to learn to play (unless the copied loadout is noobtube class).