Albizia is spectacular in bloom. The flowers are delicate and beautiful and fragrant. If you don't agree then there is probably no reason to try to make a bonsai out of it (so why did you try?)
Flowers turn to mush in the rain...simple solution, keep it out of the rain while it is blooming
Apples and oranges? Hardly. I'd say most people who try albizia do it for the flowers, just like wisteria. I'll give you the trunk thing, wisteria can have great gnarled trunks. So maybe
more like mcintosh apple versus yellow delicious.
Fine, say that. Don't dismiss it with "crap species".