at really loose $25NL tables, I like doing this too. for several reasons:

1.if you raise, you're gonna get 6 callers anyway, you're not narrowing the field
2.If you limp with AK and spike an ace, you'll get enough action from all the Axs that limped in to make up for it
3. If you limp with something like JJ, if you get an overpair, people think their top pair of nines is good

It really depends on the table, but I think this can be a profitible strategy