I haven't yet had the chance to play the new TT in the beta and I'm waiting for a chance to give it a shot. Riot may have added new elements to the map and changed the look of the map but there are reasons to what they did, I'm sure. The map is also in beta and that means that changes can still be made.
I think that adding the alters gives a nice blend of dominion and summoner's rift. It also gives more objectives that dedicated teams can focus on to get the game moving and more entertaining.
This also decreases the gains from turtling. There are now more objectives that the enemy team can get because of that fact and makes turtling costly as well as harder to do.
Again, I have yet to play the map but I am looking forward to it. : )
As Taarki mentioned above, ignoring the alters will give the enemy team a strong advantage in the next team fight. Like in SR when you get baron buff, you try to push objectives not sit around.
Should a team get both alters they will look to make a play and score an objective. It would not be wise to simply ignore the alters. : )