You're using up an absolutely vast area in your building for bike paths.
You also are forced to build everything into a ramp shape so that the bikes can get in.
Oh and alternative solution (put a bike garage on the ground floor). Is cheaper and probably nicer to live in since the people on the top floor can use lifts instead of riding an extra couple of k up hill.
The whole point of the conceptualization is to explore what cities/buildings might be like if we built bike-first. Of course it's not "practical" versus the cheapness of first floor bike garages. It's meant to be a vision of what we might do if we rebuilt things from first principles.
Certainly you could do both: have a good lift to your floor in the evenings that you could ride your bike into and then in the mornings coast your way all the way down as a fun way to start your day. Some people would even appreciate the extra uphill climb every day as an easy way to stay fit in their own home buildings.
Another thing to note here is that the conceptualized buildings are a lot wider than they are tall. The impression being that even if you had an elevator to your floor you might still want to ride your bike to your unit as the floor itself will be long enough to warrant that sort of thing.
Again, the goal here is to question design principles and it is a fair and interesting design because it asks questions about our assumptions. We currently don't build buildings more than a quarter mile wide because once inside them we assume everyone has to walk. Thus we tend to build taller buildings instead. Shorter, wider, ramp-like buildings are an interesting idea and this concept gives us a vocabulary to discuss them.
Do I expect to see these in cities any time soon? Definitely not. But it is still a neat design worth discussing, especially if it allows us to re-question old city design assumptions.
An alternate alternate solution would be to install elevators more friendly to cyclists. I imagine they would have to be larger in floor area, with wider doors, both front and back, and have different floor request controls.
I see the appeal of biking up to your own front door without getting off, but ramps may be the worst possible way to do it.
In the use case where you are carrying heavy items in panniers on your bike, you need some way to get those items from the garage to the apartment. Why not use the bike itself? And if you can put your bike in your apartment, you don't need the garage.
You're using up an absolutely vast area in your building for bike paths. You also are forced to build everything into a ramp shape so that the bikes can get in.
Oh and alternative solution (put a bike garage on the ground floor). Is cheaper and probably nicer to live in since the people on the top floor can use lifts instead of riding an extra couple of k up hill.