One downside to crabapples is knowledge. Some crabapples are well known and have quite a history. whether it being ornamental or some good human edible ones. However, there are places that have localy found crabpples. They have worked well where they are. However, usda zone range, disease resistance, chill hours, and rootstock compatibility are somewhat unknown. Some places have fireblight more, or have certain insects another tree is more resistant to. Chill hours can be effected by local soil conditions too.
My home is NY by a river in zone 5/6 is very middle ground for any kind of apple tree. However at camp I need a tree that is slow to wake up in the spring and can handle -35 deg + weather. El nino patterns, you might have a tree looking good for 5 years and the area acts somewhat mild like some warmer zones. Then get one year with a bad cold snap, or a year without much snow and the tree wakes up early.
Someone buys a tree and it gets replant issues and doesn't put on good growth, or someone has trouble putting it on a particular roostock and a crabapple gets a bad rap.
Some well known varieties are defined by hundreds or farmers experiences. Crabapples however probably have more no-spray knowledge base than commercial orchards would know.
Tread carefully with crabapples if they aren't from your general area, or an area similar to yours.
Roadside Crabapples in your local area, nothing wrong with copying them. But, its good to have a few years experience before propogating them to a large extent. Biennialism, cold and drought tolerance, relative bloom times. All this takes atleast 5 years to get a good picture. I'm still looking for a golden goose among the abandoned ugly ducklings. Very likely most crabapples varieties offered for sale have atleast 10-15 years experience with them. A few years to find a winner, then a few years more to prove it at the finder's grafted tree.
You can have a great place for wildlife without a single apple or crabapple tree. Some places do need some special offerings around abundant AG or other food like oaks tees everywhere. Without the benefit of having apple for the hunter to eat, I wouldn't put nearly as much effort in fruit trees than I do.