I've been suggesting improving Blessing of Might to also grant some strength, Blessing of Wisdom - intellect, Blessing of Light + small heal over time bonus and several other bonuses to existing blessings.
Small bonuses, but they would improve those short-term buffs, alas, there should be somewhat resemblance to balance in the game and if you take a look at those shaman buffs provided by totems then it'd be overpowered both in duration and useful uptime since totems are stationary and blessings are always up on the player for the whole duration.
So 5 minutes is just enough for paladins to be a significant asset for the group.
Paladins and shamans are both support classes, yet paladins are more defensive and shamans are sort of offensive support. Buffing something on one of them will automatically make us change something for the counterpart. Testing it out would be a nightmare nobody on the TW team want to experience.
In theory, it is all nice and easy but when it comes to class interactions you face some serious issues if not problems.