>>27833305
too much front caster to be ridable anywhere but the highway

>>27833361
You can get around this with hub steering, but that adds unnecessary complexity and unsprung mass. It's been done before (Bimota) but simpler geometries are more successful.

>>27833305
Additionally, springing the entire thing is more of a challenge. Most of the loads that have to be sprung have a significant vertical component, so making the forks more vertical than horizontal makes springing them a lot simpler. The springs can just be in line with the forks, and since steel is strong in compression, the entire assembly is strong. With a more horizontal fork you get more shear / bending forces in them, which necessitates a more robust construction (increasing weight) and additional springing/damping in the horizontal direction (adding complexity and weight).

The only advantages I can see are
>lower center of gravity
This helps lean the bike, but lean angle isn't what makes a bike turn.
>improved stability thanks to longer wheelbase
This would help with highway riding, but it's not an issue on even the sportiest of road bikes.

>>27833305
TLDR
They are heavier and more complex.
The problems they solve aren't actually problems with established designs, and they introduce a bunch of very real problems that other bikes don't have.

>>27833416
You forgot the aerodynamic are really good on these qnd a lot of foot forwards.

https://youtu.be/uk2ou5gt_94

>>27833305
>>27833416 again
Note that all of these complaints are mostly specific to the retarded implementation from that anime, and a lot of real life cruisers.
Recumbent motorcycles COULD work if they were constructed in a similar way to recumbent bicycles, i.e. with the legs in front of the front wheel to keep the wheelbase shorter. Not very crash-safe, but bikes in general aren't so who cares.
In fact, I think that would be a pretty cool thing to see.

>>27833419
True. However, aero isn't really a big issue on motorcycles since they are ludicrously powerful for their weight. Even a 500cc twin with its ~60 hp can get up to highway speeds much quicker than most gas cars, and cruise there comfortably.