why not use biamped studio monitors?

Yes, why not? It makes a great deal of sense. I've not done exactly what you're proposing, but something similar with a point source tri-amped set-up. The performance/cost ratio is very high. Getting the passive crossover out of the signal path between amp and driver is just one of the big advantages.

But you asked why NOT? Cosmetics, brand name recognition, a slightly more complex set-up.

There are those in the narrow dispersion camp, and those in the wide. Narrow certainly has the advantage of less room interaction. Either way, the off-axis response needs to be linear to preserve the balance of the reverberant field.

I listen about half to classical, from Renaissance to 21th century, chamber to full orchestra, and half to jazz, leaning more towards small group. As for near-field listening distance, about 6-7 feet, but I prefer more distance for orchestral works, about 9 feet.

Regarding bass, the best I've heard is dipole—it requires a lot of equalization to get flat. The next best is acoustic suspension. It often requires some EQ or a higher system Q, which I think is why most speakers rely on the internal resonance of the enclosure to extend and boost the bass (ported bass reflex), unfortunately at the expense of critical damping.