I think that the Alter are an amazing piece of the map for several reasons. One is that you can get on an enemy alter to bait them into stopping you, and gank them in the middle of their gank. They do provide a pronounced bonus but not anything that can't be overcome, even late game they are nice but essential. I have had many games where my team decides to just let them have the alter, and we were winning. I like the nervousness that you feel when stealing an alter as well. Are you going to get attacked, or are they waiting to ambush you afterwards, or are you just going to get away with it? It is different it is fun, it needs to be on a slightly larger map.