Unless you're clued in to what the manufacturer's thoughts were in the proof of concept, it's not really possible to guess why one product has one type of mic connector and another has something else. Sometimes manufacturers have a "style guide" that defines the form factor and says something like, 'all of our equipment will have compatible accessories.' I know that marketing types get paid big money for, make a big deal out of, fonts and logos to the extent they have pushed approved color combinations, shapes, etc. (B.S. Bingo term: "Branding")
To that end, this could be -
The engineering group came up with the design independent of anything else,
The form factor group decided it "has to be" this kind of connector (for whatever reason... usually because of expense and parts availability).
Corporate/marketing decided to go off on a new track for accessories independent of legacy products,
Or, none of the above.
Yeah, it's cheap. The clippy things break. And Yaesu's mic cord materials seem to disintegrate in hot weather climates (been through three disintegrated mic cords in my daughter's car in 5 years).
The other thing on Yaesu's overall product line is that they seem to have products that are all over the map. Some of their radios are outstanding, easy to program and use, and others (like the FT1500M *choke* *gag*) are better suited for plinking.