But then you guys have to think, sometimes its not always damage that gets the kill (yeah I know it sounds weird but hear me out). Often when I play my team goes for a gank, only to have the enemy escape with little health. Or sometimes theyre being chased and we come in and turn it around. This isnt due to damage, but often disables/and slow. A well timed disable/slow can massively affect team battles, which in turn affect the game. And this disable might (and most likely) comes from a support character, whos damage output is close to none but it is only because of them that the team is able to get the kill. More often than not, people underestimate this support because without them, a Yi could just chase you across the map. I honestly think that this character is one of the most important on the team.
In my opinion, if you whine about kill-stealing you should just stop playing. Of course there are some exceptions, but people need to learn that DotA-type games are team games. As other people have said, sometimes you have to give the kill away. Give it to the Soulstealer, give it to the carry. Late game, theyre the ones who you'll be relying on.
But yeah, thats my two cents. I dont think more IP should be given out for kills. If anything, more IP should be given out on who destroys the most turrets or something =S