It's probably because you're getting older, so the brides and grooms getting married have more money. Their childfree friends have more money and so things can be more lavish if they are hitting the average disposable income from the group. When I got married, my hen weekend was at a spa, but then all the female friends I invited could easily afford that and none of my friends had DCs yet (although one of DH's did) so childcare wasn't even considered.
That you've got other weddings to go to suggests your at the stage in your life when most of your friends are getting married, you might be unusual that you did it earlier than the rest of your peer group, but for most people there's a period of 2-3 summers when you spend a lot of time going to weddings and hen dos, but then it abruptly stops.
After several years of weddings, some being 3 weekends on the run, I haven't been to one for over a year now. Realistically, I've got 1 engaged gay couple who ae waiting to see if they have a civil partnership or wedding so no date set and one single friend, and that's it, all others are done and dusted. Until it's DC's generation getting married I can't see myself getting another wedding or hen invite after that last two. (assuming they ever do get married)
Perhaps when you did it you were one of the first in your friendship group so your friends had the time to fuss, if not the money. However just because there are a lot of people in your life getting married right now, doesn't make that day any less special for them.
But also remember, these brides haven't arranged their hen or wedding deliberately to annoy you, it's supposed to be a nice thing, if you don't want to go then don't. But don't get an arse on because you put pressure on yourself to go to everything and spend a lot of money on gifts (not all our guests bought us gifts or spent a lot of money). Not all the woman I invited on my hen do made it. Not all weddings we've been invited too we've gone to. Not everyone we invited to our wedding accepted.
It's ok to say no to some of these invites, but it's not ok to accept then grumble that it's not been arranged in a way that's best suited to you and your lifestyle rather than the bride/groom and the bulk of the other guests.