I don't see how there could be a debate here.
The gaming industry always worked like this on similar games.
The controversy is justified in solo games having MTX like AC: Odyssey, not in multiplayer games like SoT.
There's no "they don't charge for dlc because they know they couldn't get away with it if they did" argument to have here. For one, you can't possibly know about that and for two, that's just not true.
Elite: Dangerous "got away with it". This game has MTX for ships skins AND paid extension that fragments the playerbase. They got away with it just fine. I saw nobody in the forums there complaining. And the game was in the same state at launch than SoT was at launch.
Thinking that the 50-70€ you paid, we all paid, almost 1 year ago will be enough for the game to be updated like it did for another year or plus is just naive. New sells won't be enough to.
When I paid 70€ one year ago on the MStore, I had no idea that I would fall in love with this game that much. I also had no idea how Rare would be so great at updating the game. Look how the game has grown in 11 months. The game had almost no content 11 months ago and now there's plenty of things to do on the sea. In 11 months, SoT has grown far better than Elite: Dangerous did in 2 years, wich was in a similar state may I recall. And I paid ED 120€ for beta access + lifetime expansion pass. Still had to pay for skins though.
But I'm not complaining as I've spent 800-1000h in this game alone.
Same thing for SoT, this game has given so much extraordinary moments that I just need a reason to support the game a little more, like MTX.
This is how the industry works. We either continue to have free-dlc and pay for some cosmetics MTX, or we don't.
Now to answer the OP, I'll gladly pay something like 5-15€ for a beautiful pet with awesome interactions. One thing I would find absolutely AMAZING is having a parrot that can repeat some of the words you're saying with a little "parroty" voice. Oh man, I'm laughing just by imagining it !