I felt the same way when I got my first 87U. It's rather unexciting, which is compounded by all the hype about how incredible it is. It simply isn't the kind of the object that you're excited to use and can't put down.
Where it really shines, in my opinion, is in daily extended use. After using it for a while I started to really like how easy it was to live with.
It makes a very pleasant noise that won't get irritating (won't bother anyone else), looks inconspicuous (doesn't draw attention for theft or conversation), is buttery smooth, and the tactility is a nice hump rather than being a linear with a notch in the middle. It's easy to use it in any situation and for any purpose, for any amount of time.
HHKB is a more interesting Topre experience, and I'd say more fun to type on. Any keyboard enthusiast will have a collection of more interesting and desirable keyboards.
It's like having a collection of vehicles. You can have fun roadsters, motorcycles, classic cars, etc, that all have their time and place... but most people would have a hard time finding a day to complain about having to drive every day or long distances in an S-Class Mercedes. There will always be times when you're tired, not feeling great, have a headache, aren't interested in dealing with your loud roadster with a harsh ride and finicky gearbox, etc...
I think that's the best way of describing my experience with the 87U. It isn't for a lack of more interesting keyboards that the 87U is probably the one I would keep if I could only have one.