Based on the experience me and my relatives have had with smartphones so far, I believe that if you have enough money, and you use your smartphone the way most technically competent people these days would, the absolute minimum for the amount of RAM is 2GB (well, at least 1,5GB if you are on a budget). 1GB RAM phones are incredibly cheap these days, and I believe the same will be true in a year or so regarding the 2GB ones.

What are the advantages of the priciest phones, then? There's less and less, and for me they're mainly the things I either don't care about, or can at worst case make a sacrifice of, for paying less for the device. These would include:
* having a "good enough" camera instead of a "good" one * the phone might be less elegant since the smartphone producers tend to leave their best designs for the priciest models * it might have a worse screen, or a lower resolution one - although I prefer longer battery life over a nice screen * sometimes you basically have to buy a Nexus or a very pricy phone, if you want to have a good custom ROM support, given how the cheaper SoCs don't seem to be supported very well * there might be some premium features missing, see below for an example.

That's all I can think of so far, do you guys see more reasons to buy a premium device instead of something cheaper?

The only thing that'd make me even consider pricy phones these days would be headphone audio quality for example. My Honor 6 is a really good phone for my needs, and I have only a single complaint about it: the audio is quite bad. After using HTC HD2 and Galaxy Ace 2 (the latter wasn't even a high-end phone at any point of time...) which both sounded really good on headphones, I am really disappointed with Honor's audio quality.