I agree with your first point. I do want to refute your second point. How often do you see a dev kit out in the wild, especially a Rockstar one?
Nah devkits are actually cool though IMO, you actually get some genuine clues into how the game was built from the ground-up and potentially have a shot at source code, so that's neat. I just don't find beta builds all that alluring or fascinating. Plus it's a piece of unique hardware which I'm a sucker for, those old 90s workstations that were used for graphic design/etc are cool as fuck to me. For instance, the SiliconGraphics Indigo workstations from back in the day, or SGI, are cool as fuck. I believe those machines were used in the creation of most of the very early 3D/CGI animated movies like Toy Story, Bug's Life, and most of the other stuff Pixar put out at that time.
I dunno, I think they're pretty neat, and they were super fucking expensive at that time. I believe some of the most capable models were $36,000 new.
On RDO making less money than GTA V Online, I'm guessing that's because you just can't exactly pump all kinds of crazy microtransaction shit into a game set in the old west like you can with a game set in the modern day. In GTA V you can add a whole bunch of supervillain or near-future shit like rocket bikes, flying cars, hover tanks, laser guns, submarines and jump-jets. Whereas in RDO, what can you really stick in there to entice 12 year olds to buy RDO Gold? A slightly faster horse with a unique coat color? A sleeker looking wagon with a Gatling gun in the back of it? That stuff isn't very exciting, really. I guess if they really wanted to get wild they could stick an early automobile in there [they did exist in a very limited quantity at that time] but the engine wouldn't even slightly be built for that.
Something that really pissed me off about RDR1 is that they actually HAD the Model T [or something like it] in game, the model was there and perfect, you even get to ride in them on several occasions during missions, but they didn't make any of them fucking drivable or available in sandbox/outside of missions. They easily could have done it, and I'm sure now that it's on PC there are mods for that, but it would have been cool as shit to be able to drive them. They even had a "distance/number of miles traveled by automobile" in the stats menu, but it was always going to be the amount of miles from the missions, which are basically just cutscenes of riding to the checkpoint that can be skipped. I'm also pretty sure I remember hearing that all of the driving physics and controls were even included in the source code, but they cut it for some reason.