I'm not sure how I feel about the OP's proposed change and I feel similiarly to the way ploki122 feels.
This change could only serve to make the proverbial "dominant" team in any given match that much stronger, while the other team is at a loss. Even if this wouldn't be the case, this would encourage "stale gameplay". What I mean by this is potentially both teams would just tip toe around until baron spawns and play "Ward Wars" @ Baron while keeping their lanes frozen. Any and all team fights would happen near Baron nearly 100% of the time.
I feel that this proposed change is also counter intuitive because it only encourages "All or nothing" gameplay and strategy, which also affects powerful and viable team compositions. I also feel that the Risk/Reward analysis is also a bit lopsided. Since camping Baron on cooldown yields such a huge blow to the enemy team in addition to granting the buff, I would estimate that more reckless Baron attempts would arise from this. I say that the Risk/Reward ratio would be substantially off because of the fact that so much time would be spent around Baron, the other portions of the map, such as Red/Blue creep camps/Wraith/Wolf/Golem Camps, and even CS in lane will be neglected to facilitate this small change to what killing Baron does, which in my opinion would change the entire meta of the game.
To sum it up, I don't really think Baron should be buffed. The reward for killing him is plenty strong, and is still defendable as long as you aren't in a situation where say, all of your inhibitors are down, or a similiar scenario.
I am interested in these proposed 'changes' to Baron though.
EDIT: I feel that the OP's proposed change wouldnt exactly lead to more players pushing for more map control, I feel that it will push players to have more Baron control. And in this change, Baron Control > Map Control due to the fact that killing Baron damages enemy towers.