Publicly known prices are one of the elements of the ideal free market, as described in economics textbooks. It's well-known that free markets encourage competition and generally push the margins of vendors down, even to subsistence level, which is great for consumers, but obviously not attractive for vendors. So, naturally, the companies do everything to move away from the free market as far as possible - i.e. have a monopoly/oligopoly if possible, or introduce super-convoluted contracts that the average consumer has no chance of understanding (EULAs etc.), hide their pricing etc. In general - the more muddy the situation is, the more it favors bigger players.

Possibly, but not necessarily. You might want to lead with your value before price, especially in an industry where it's difficult to see at first look what the differentiators are. Alternatively, public pricing could start price wars, leading both companies to unsustainable pricing. Or maybe you want to be able to give strategic customers specific discounts. These aren't pricing strategies to make sure your customers get the best price possible -- they are designed to allow me, as the creator of some value, better control over how that value is perceived and deployed.

For a business, you want to build relationships, not just have transactional customers. The more custom or integrated your solution is, the more important this is. (Also, it's the best way to make sure your customers are deriving the most value from your product, which is a win-win.)

Yes, competitors can do that, but that additional friction means they won't stay up to date, and you have a chance to discover what's going on.

As a customer - in this case I don't want to build "relationship" with some random middleman reseller.

I know exactly what i want and rather avoid wasting time on upsells thrown at me.

I understand that sales departments strongly prefer "bait and pimp" vs. "sell and forget" strategy - but some customers and often significant ones will give business to competitors if former is the only strategy to generate revenues.