Well, I'm also thinking about third party retailers, which usually don't stock as many of the upgraded models as they do the base models. By virtue of simply having more stock available, the base models are usually the ones that go on deeper sales, and they're also the ones that are the easiest to buy on the second hand market.Not really. It's a way to force the SSD upgrade, improving the ASP.
Upgrading the base spec does make good machines more accessible to people who can't afford to buy them new. My very first Mac was a used Mac (my 2012), and I would have never been introduced to the ecosystem if the only option I had as a student going into college was going brand new. That's part of why I pay attention to the second hand market I suppose, it's what ended up introducing me to the Mac world of things (and I'm glad it did, I haven't looked back since).