I agree in that, these days, I don't see myself wanting to upgrade a laptop's RAM before I'd just replace it with a newer machine. While it would be a nice bonus to have the option, realistically I imagine the 8 GB of memory that comes standard with the baseline MacBook Pro model would be enough for anything I'd personally want to do with a laptop in its lifespan, and I would be willing to sacrifice memory upgradability for a slimmer design, for example.
However, I think Apple (and other laptop manufacturers) cross the line when they ship soldered-in batteries with their laptops. Batteries are consumable components that are guaranteed to degrade over time. Unlike RAM, which, assuming Apple sources it from quality vendors, you can expect to last for many years, laptop batteries will definitely begin to degrade within a few years, and will, over enough time, render the laptop unusable. Apple is producing $1500+ laptops with a non-replaceable component that will, without a doubt, eventually break down. Your options at that point are to buy a new laptop, or to send it to Apple so they can charge an arm and a leg to replace the entire top case instead of just the battery (as that'd be impossible). You should buy a new laptop when you want to, not because you "might as well" without the option of battery replacement, and with Apple's "repair" option costing a quarter of the price of a new one.
Though to a lesser extent, it also irks me that the SSDs are soldered in, not necessarily because I'd want the ability to upgrade them post-purchase, but mainly because your valuable data lives there, and it will become trapped on a dead board if something goes wrong with an unrelated component. Even if failures like this are rare, the threat of data loss while using a MacBook would still concern me more than while using a laptop with a replaceable SSD. I believe Apple has a data recovery procedure, but you'd still have to send your laptop to them and cross your fingers in the event it dies, whereas if the SSD wasn't soldered in, you'd have the option of manually recovering your data, or taking it to a repair shop where they could do it for you.
I would love to see a MacBook Pro with, at the very least, a replaceable battery (but especially with a replaceable SSD as well).