View from the back-end.
If I were a Boeing 737 salesman, I would try to sell you the Boeing 737-800 in comparison to the A320 because that is my job, regardless of all other considerations. Claimed unique selling points and technical comparisons between aircraft types are all readily available to prospective purchasers these days, long before I arrive with my box of sweeties, samples, and smooth talk. Prices, I suspect, are a different matter and depend entirely on head-office wheeling and dealing in which I am not involved. My role as an (alleged) salesmen is to toe the party line and carry messages - much like a humble Zulu spear-carrier in the old days. And heaven help me if I get the message wrong!
At the end of the the day it is passengers and freight companies who pay for the aircraft they prefer and their requirements are pretty much standard, hence the similarity and blandness of modern aircraft (and motor vehicles, for that matter). Within those constraints, aircraft manufacturers charge clients whatever they can get away with and their clients pay as little as they can. Its a big bazaar, and pilots are just hired hands driving all those air buses, vans and lorries. Sad for all you commercial aviators after years of expensive training, but that's the way it is. Yours is the responsibility without the power. Whether a Boeing flying grommet is better than its Airbus equivalent is irrelevant to me, the salesman, so long as people buy my company's stuff. But I write only from the perspective of an aviation user, so what do I know!