As a millenial myself, and a rather new diver, I can't really talk about the changes in the scuba industry. But here is what I can say about how I (and my friends) came to scuba diving, and how I am approaching it.
As has been mentionned a lot here previously, we (when I say we, I mean mostly me, but what I also see amongst my friends and other people of my generation) value experience above things. I don't really know why we differ on this subject to previous generations, but I believe one of the reason is that because we grew up in a consumer society, things are moslty disposable item. Something is to be bought, enjoyed for a while, thrown, and up to the next. Therefore, the are just tools, and not important. More important than the object in itself is what they offer us as a "user experience".
Also, we are a generation that moves a lot. We grow up in one place (or several - I'm an expat kid myself, so maybe not really representative), study somewhere else, than work in again another place. And when you move a lot, you don't want to own too much stuff. As mentionned previously, it's cumbersome. Ergo, again, the fact that we value experience. It's something that enriches everyone, yet doesn't take any space. So a lot of us would prefer to just rent gear rather than invest in some that would take space, is expensive, and will change soon (I know that good dive gear last long, but we are so used to planned obsolescence and cheap stuff that breaks soon and changes in fashions that it's hard to integrate that in our habits. It might last for a long time, but will we use it for a long time?).
Then, we are a digital generation. Everything we "own" fits in a cellphone or is in the cloud. Also, internet allows us to see everything. We see what is happening on the other side of the world, everything. So we want to see everything in person too. But there is just so many things to do and try! So much we are missing! So we just zap from one thing to another, to enjoy as much as we can. That's why I actually pretty like the fact that most certification agencies cut lessons and classes and certifications in small bits. I can do it one bit at a time, at my rythm, when it's convenient. Although I'll admit to having discovered recently the joy of taking things slowly, and I'm still trying to adjust for that.
Next, I think we are a generation that value lifestyle and convenience. We grew up in a world where everything is just one click away. Everything is processed and pre-packaged and offered to us in a immediately usable way. Unfortunately, I haven't found a way yet to have the ocean delivered to my door (in 24h of course, which is usually the norm in China for online deliveries), so our way to the ocean has to be convenient and easy. I think it's Wookie who mentionned previously a dive shop that offers trips, everything prepared, no hassles. That's what I am looking for if I am paying someone to do things for me. If it's only booking a hotel, flights, etc., I can do it myself, thank you. If I pay for a travel agent (or LDS) to organize a trip for me, than I don't want to have to think about it in addition. Also, a lot of us grew up as the center of our parents world, i.e. of the whole world. So we want personalized attention ^^ (well, that might be because I spent half of my life in China ;-) ). I'd much rather have someone to help me organize a personal trip, or for a small group, tailored to our needs, than join a big group. Unless, as also mentionned previously, this group offers something extra to just the trip (atmosphere, unique experience - again - , etc.)
And I think a last important point is that a lot of my friends have unstable careers and situation (I put myself aside on this point. I consider myseld lucky, with a good and stable situation, but it's pretty exceptional amongst my friends), we probably won't have any retirement when we get there, salaries are low for youngers people, we change jobs often, so it's not easy to find the funds and the time to feed and expensive hobby. For example, a friend of mine is at his third job already this year. We were supposed to take him on a trip for a DSD, but then he had to cancel because he had just resigned from his second job and had to pass interviews/was out of cash instead. Basically, most of us have to make a choice and decide on which experiences we want to spend our cash and time, and we will chose the one that will give us the most value for our money/time. Scuba might be expensive, but I think if we are shown that we can get a great valued experience from it, than I think we are ready to go for it.
So how does all that relate to my scuba experience?
Well, I got OW certified a bit as a "bucket list" item. I was curious about it, it was something I wanted to experience. So a friend and I went for our OW (at least we would get a certification that would last us for a lifetime, contrary to just a DSD). But we went to Boracay, which is not the best known destination for scuba diving, but is a rather "complete" destination. Why? Well, in case we hated scuba diving, there would always be other things to do ^^, others experiences to enjoy (for example, we also went on our first helicopter tour during this trip). And then I absolutely fell in love with diving. So even if I started believing that I would only be a "resort/holiday" diver, in my case, it ended up being much more than that. So I think it's OK to start like this, you never know where it might take you ^^