A base price can only be made public if there exists a base price that would be common among customers - however if it's not priced as a commodity, that's not the case, there simply is not a base price that could be disclosed because there is zero expectation that there should be "the same service" available for the same price, or that there is some base price from which discounts are negotiated or something like that. They want to preserve the ability to have wildly different pricing for different customers, and publishing (or even having internally published) some fixed base price works against that.

If they want to sell their services as custom services, that's the business model - and in this case, they want to make a clear point from the very beginning that this is not a commodity and every deal is a bespoke deal. Even if the technical platform is the same, every business relationship is custom and individually negotiated, with zero expectation that the price you get is in any way related to the prices someone else gets - sometimes that works against you, sometimes that works for you, but that's the business model they've chosen.

It really depends on the nature of the software and the target customer as to whether that makes sense. The spectrum of what "SaaS" is, is just so insanely broad that it's hard to make any sweeping statement here.