My reasons for not having played for some time and some of these may apply to others:
I don't really neeeeeed any more stash
The work involved in running a bingo (although it needn't be as involved as some people do, I'm sure that just numbers without any reference stuff would be acceptable, if not so interesting)
And of course the cost of providing a prize, although I seem to remember we used to provide a prize from our own stash which, if acceptable, would be more attractive to some members as they would not have to outlay some money which they perhaps could not afford.
I think those are pretty valid reasons, but easily overcome.
If the player who wins doesn't need any stash and the prize was a gift certificate, they can always buy something for someone else - or buy needles or practical things instead of stash. And if the prize is something from the host's stash, it can be kept as a lovely reminder of a fun game (until put to use).
I felt a bit nervous about the first Bingo I hosted, but you're right, it doesn't have to be a super involved game. Simplicity is good, too. And as for the prize, if it comes from stash the only expense to the host is postage. Sometimes postage can be expensive, so there's always an option of saying the prize is stash if it is mailed within the host's own country and an e-certificate if it would have to be mailed internationally and the postage would be more than the prize value. Does that make sense?
All that said, I hope we get more players because Bingo really is fun. I'm glad I finally played - I watched a few games before getting up the nerve to join in. What got me hooked was the fact that the players seemed to be having fun as the daily numbers were posted, sharing their success (or lack thereof) each day and commenting on the daily picks.