That shouldn't be the case. I don't care if you want to cheese the system for every extra point of DPR, but someone casual who wants to multiclass for a character concept shouldn't end up with "will often be worse."
Well that is the way the mechanics are and there are always tradeoffs. Moreover this too is not unique to multiclassing.
Moreover when it comes to multiclassing for concept, the ability score minimums are really the biggest impediment to that, especially with Rangers and Paladins, not the players.