The 2008 and 1988 911 have virtually no components in common. Whilst the name has remained the same it has gone through 4 major redesigns, gained 4WD, a change to the cooling system..... and more. They may share a common layout and form but that's where the similarity ends.
And a modern rev (1.5B) has different fabric, different spars (race rods are nothing like classic Advantage), not to mention a different cut to the sail...in addition to a carefully designed panel layout (with rotated grain on every panel) to optimise flight characteristics and aging. From a distance, a 1988 Rev I and a 2008 B-Series might have a common layout and form, but that's where the similarity ends.
If someone does come along with something genuinely new but all it gets is "yeah.... but it's not a Rev." then there isn't a lot of point. You've seen Steffen's Knockout I'm sure - it does non-Rev. things - interested or not ?
Hmmm. Genuinely new quads. How about the Synergy Deca or the Symphony, from Merrick Munday, both of which were patented. Neither of these flew anything like a Rev. Both were used in major competitions in the US and had major followings (well, the Symphony less-so, but I certainly saw it around a lot in the mid-90s). Obviously, the Airbow has already been pointed out ad nauseum. There's also the Spirit by Steve LaPorte. I've owned most of these and flown all of them many times. The only one that I'd ever choose to fly over a Rev on any given day might be a Deca. Might.
The point is that plenty of people have tried plenty of other interesting and unique quad configurations. Some of them are still around, some aren't. The fact that you can't commercialize
a Rev derivative should have no effect on innovation in the Quad space: assuming, of course, you can come up with a competitive design. And that seems to be the tricky part.
I've seen two major design tweaks to the Rev over the 19+ years I've been flying them. The first was when someone chopped off the bottom tips of a kite and used two verticals on either side. I don't know if Revolution Kites came up with the same idea on their own or not, but they've commercialized it as the Speed Series.
The other major tweak has been the use of quad/magic sticks (aka training wheels). Rev would be willing to sell those if they could manage to not lose money doing so. As it is, they're available as an after-market addition that's easy to add to your kite, and Revolution certainly doesn't care what you do to their sail after you've bought it from them.
I write as someone who has made my own design tweaks to my favorite Rev, the II. While the IIs I build and fly can use a stock Rev II frame, the sail is cut differently and the flight characteristics are different. Do I think I've innovated anything? Hell no -- I think I've made a kite I personally prefer to fly.
This "innovation" thing that keeps being brought up is nothing but a red herring. Inventors have opportunities. If they're unable to best the Rev design, then we don't need their "innovations." And if you really think there's some value you could add through innovating the Rev platform then by all means buy yourself a factory rev, make those mods, and re-sell it...your innovations will surely be worth the premium you'd need to charge to make back the costs of buying the initial Rev, right?