I read the original post slightly different. They took the time to register and type out a question, seem to me, despite what they say that they're on the fence.
If I totally dismissed a bike brand/model I would not post on that makes forum, I would just moved on.
Sounds like they've giving it a lot of thought and not sure if they should like it or not. When I was looking to trade a lot of my fellow riders asked me why and stated some of the same, 'they for old or disabled riders'.
I posted here looking for Spyder riders input on why they ride and I got great feed back, obviously as I ended up getting the RT.
I have seen many times where people have first hated some thing and ended up with one. My own first opinion of the Spyder was very much like the OP's, I hated it, thought it looked like a lawn mower going down the road, I made comments to my wife and friends that I wouldn't ride one unless I was too old to hold up two wheels. Now look at me, can not get enough of the Spyder, absolutely love it.
So to the OP;
You have to look at the Spyder slightly different, obviously is not two wheels but it is a great bike to ride. I'm 48 in great health, been riding bikes since I was 12 both in Europe and here in the states. Started on dirt bikes, then went into street legal mopeds, trust me being governed to 35mph is no fun but still my friends and I went all over the England, from coast to coast. I had a lot of bikes in my riding years, Vespa's, Yamaha's, Suzuki's, Honda's and Kawasaki. Scooters, cruisers, sports, touring bikes etc. I traded my last ride, a 2006 Goldwing for the Spyder RT and have not regretted it once.
The Spyder is different its not a knee grinding bike, but it is still great fun in the twisties and absolutely great for touring. A good comparisons already made by Lamont is comparing a dirt bike to an ATV. I have ridding both and both are great fun, I still have ATV's (no dirt bikes any more), I ride in Maine and New Hampshire with my sons and have a blast. I'm biased as most will be on here, most own a Spyder already or are looking into one, but I have to say this is most fun I had for years. I have been riding for over 35 years and was starting to get board, been there done that sort of attitude. The Goldwing last year stayed mostly in the garage and I even started to wonder if I wanted to carry on ridding any more.
I may still be in the honeymoon phase but the Spyder as given me a new lease on ridding. Went to Americade, Laconia, Magog not too mention all the local riding I have done this year already. Been ridding with a group of New England riders through Connecticut, Rhode island, New Hampshire etc and its been a blast. I've had no issues riding through Vermont Mountains with trailer in tow keeping up with two wheelers. This is just different enough to be just darn right fun, its a great feeling that I can not explain. I bought mine for the shear excitement I felt ridding it, all the safety features are great but I would have bought it with out ABS and the stability control. The fact there built in is great but was not factored in when I made my mind up.
See if you can get an extended test ride on the RT and keep an open mind, you may have a blast. Remember owning a bike is not for life, you can trade up, down, side ways at any time. In a perfect world with unlimited funding I would have kept both the Goldwing and bought the RT. But to be honest if I had a choice to ride either as I leave the house, my choice would be the Spyder.
In the end if the Sypder is not for you so be it, if every one like the same thing it would make for one boring world. If your Harley is your dream bike then your very lucky as you already own one. I think I have found my dream bike and I'm lucky too, it is sitting in my garage right now. I have not yet met anyone as been totally negative about the Spyder, some have said its not for them but most have stated it looks fun.
ride safe.
harry