It depends, there are certain hands you still shouldn't play because even an ideal flop w/ those hands against numerous limpers is very dangerous. For example, lets take 4-7 offsuit. Are you going to chase your straight draw? You are going to have to be super careful about doing so, because your straight simply cannot be the best possible hand. This makes a difference.

Also, what about when you get 2 pair w/ your 4-7, but then get a lot of action? These are the nasty situations that playing these rag hands puts you in. You want to limp w/ hands that can't cost you much money, but can make you a lot. For example, 6-7 suited is nice because you can hit a straight that is the nuts, period. You can't do this w/ a lot of these marginal hands. It seems like splitting hairs, but it makes a big difference.