I read somewhere many years ago that one stadium series event was essentially the equivalent of like 4 normal arena games. So, no doubt, that's why they keep doing them. The Dallas outdoor game new years day was said to have 86,500 ppl attend - that's a crap ton of $15 beers...! So, some may feel it's being overplayed - but if they're continuing to do it - no doubt thousands of others don't think that.
A game at Target Field would be pretty cool - but like someone mentioned - it would be somewhat of a novelty event - something to attend at least once to say you've tried it... Too bad they couldn't match that up with Hockey Day MN...