In the vast majority of games, the life that your opponent gains from you nuking their creatures with Swords to Plowshares will not amount to much, unless theyre playing a black deck with life-to-resource cards (watch out for Toxic Deluge or worse, Yawgmoths Bargain !) Swords to Plowshares isnt a particularly expensive card, and its very easy to find
Thriving Rhino: [Category 2] ETB yield is 2 Energy for 3 mana, then you can spend 2 Energy for a +1/+1 counter
Secondly, a lot of folks out there aren't comfortable with the idea of exiling stuff from their library
Also, like Losheel, you can make tokens instantly to draw each opposing turn too, only that's easier since so many token makers like Raise the Alarm are instants already, and lands will make tokens like Castle Ardenvale
His Barrow-Downs (Bojuka Bog) and The Shire are also quite good