[iggymcfly]

You don't want to "always" open with a raise. There are a lot of considerations to take into account. One is the number of shortstacks out there that might be looking to limp-raise AAxx and would be getting most of their stack in. Another is the quality and type of your hand. Something like TTxx no suits might be worth a cheap look to try to hit top or middle set, but isn't something you want to commit a lot of chips to preflop.

In general, you definitely want to raise a lot of hands on the button when there are limpers, as raising the stakes when you're in position is very important in PLO, but doing it every single time is overkill and can put you in bad spots.