That would be the most satisfying solution. Just adding a mechanic that prevents skipping (auto aggro whole party, closed doors, etc.) would only cause unhappiness. At the moment, trash mobs are mere obstacle that don't have any value what so ever (even worse, besides the huge time investment, killing them actually costs you money in terms of repair bills). Skipping them, if possible, therefore is the logical conclusion .. because there is no reason to do otherwise.
So the best way to solve the "problem" would be to add an incentive to kill trash. That way we actually have to make a decision if we want to skip (faster tomes) or kill (money, xp, other items, ... whatever incentive you can think of) trash. Having more options would be a good thing here.