If we're going to be forced to upgrade useless characters

At least make it worthwhile. Why should I be paying 5 times the cost to change the trainer, when he gives the exact same boost at 5k talent vs 25k talent? Add more trainer abilities. Eg, Architect Seth grants an additional turn of bleed at 20k talent, or Typhoon gives one more Blast Gem at 20k talent. Stuff like that. Otherwise, we're getting doubly penalised, by first getting resources drained to take up a character who's useless past the week they're required, then again when we have to pay extra to transfer them around as trainers.