I think that it's a really constructive opinion on what exactly changed in Warframe's overall feel from a player's perspective.
I play for fun myself, as do many of my clanmates playing since the initial open launch when you could still buy these founder packages with Excalibur Prime, and yet none of us is Mastery Rank 28. 🙂
It's true that given our accounts have been present for many years we're not focusing on the grinding part of the game - if something we like is around, sure, we'll pick up the materials for it and craft the thing. We also did get Ivara the classical way through Spy missions. However, in the end we don't care if we're MR 15, 16, 18 or 23 and so on.
This is where I believe Warframe development should not stick to the 'everything adds to the endless MR grind, and when you finally hit MR 30, then we'll just increase the max to MR 40' (not an actual quote, but business assumption). The question is, why would anybody care for that and focus on the tiny number as something major? I think that there's no proper way to answer that, as it's too subjective. I've seen people go for it for more initial mod space on their stuff at rank 0, however at some point there will be nothing to level (like at current MR 28) so that mod space is just a figurehead impression of progress. Now, don't get me wrong, I prefer that MR gives that tiny modspace boost and some really unnoticeable utility boosts rather than straight up stats, as that would be a balancing nightmare and transform the game into an eastern grindfest where strength is measured in thousands of hours spent and/or sneakily botted.
During my gameplay I've often seen a higher MR player bash a lower MR player while openly expressing their MR difference (superiority/inferiority). Relating to my above text that would mean at least a part of the community uses it to measure or add up to the personal ego - I'll not go into detail whether it's compensating for something or not. So where the heck am I going? Well, the answer is - I think that a considerable number of the playerbase focuses on this archaic, endless grind style Mastery Rank, instead of going for their own fun and enjoyment that's not publicly measured or shown, but rather felt on the inside (imagine like, "Aaah, this Corinth sounds and shoots too good, it's ballistic music for my ears"). Who or what should be blamed? Well, nobody! Blaming isn't cool, even if there are visible, considerable design problems. So based on reading the above what do we know? That the only kind of progress is tied to a system of endless, mostly purposeless grind. That from my previous post there's something wrong that happened with the old style enemies who could just keep inflating tens of levels above a hundred and would still be just an uninteresting cannon fodder without any kind of personality.
What to do then?
One might think at a glimpse "let's add power meaning to MR then to have progress" but let's stop there! Did we come here to play Tibia / Metin / Black Desert Online / any other semi-infinitely power-scaling MMO game? Hell nah! We came here to play Warframe, so let's stay on playing that game in its own, unique design. Player freedom, lots of customisability, and once more - unique design; all of it and many more characteristics make it one of the best free-to-play games.
I mean we could fiddle all we want by attempting to give MR a purpose, streamlining player progress better while avoiding the semi-infinite grind, etc.
However the actual move should come from the developers themselves, I won't pretend or claim that I know more than them about their own game - after all they have the data in their hands, and this is why that data coupled with many awesome ideas passing this forum could create great things together.
Peace for now, gotta work. 🙂