Look, I'm a sociologist so I totally get where you are coming from, but your thougts are mostly tangential.

Catalonia can enact his own laws, and it does so. There's very little substance if you say "being freed from the chains of Spain". There isn't any massive difference in the understanding of the world between catalans and the rest of the peninsula. You could pimpoint some laws here and there, and some simbols, but it's pretty much it. There's no systemic repression of Catalans of any sorts because of speaking or being Catalan. I know that an independence supporter will disagree and is willing to paste thousands of links here, but IMO from the big picture there's no much substance.
They are not loosing autonomy as you said, as it's been happening quite the opposite.

There's a lot of stuff happening daily and a lot of propaganda going on. The Catalan government is very good at this, and it's difficult to make foreigners understand how much effort they actually put on this. To give you a glimpse, yesterday they sent their supporters to occupy the Barcelona airport. Politicians are not stupid, and they know that place is guarded by national police and the military. Some time later, as it seemed such actions wouldn't yield any PR material, they've sent their own police. That's the videos foreigners have seen in their media. Obviously, the majority of them don't have to know that Catalans have their own police, and they were sent there coordinated by their own government, that it wasn't spontaneous. And most media won't clarify it.

Today, their explanation for internal consumption is that they had to send the Mossos d'esquadra (Catalan police) because they had to "protect the demonstrators from themselves", they were afraid to be accused fo sedition again and some other BS, that of course will be noise tomorrow.

I know there's enough speculation in the last two paragraphs, but I worked for them for some time, so I know how they think. And that's my take on it because, if it wasn't for that, it would be absurd to send your people somewhere and then beat em just because.

And this stuff is happening on a Weekly basis.

Now, you think the most pragmatic solution would be just accept "the fact" that Spain lost Catalonia, and that it has to become another country. Now, what happens with half the catalans that want to remain spanish? Do we just forget about them? What if they become violent? What would do the Catalan Government if they become their own country and half its population does the same they have been doing? What if they win elections and want to rejoin? (I forgot, that wouldn't be possible under the new catalan law, they wanted to make parties against secession illegal), are we going to split and join multiple times because of this?

I mean, there's a lot to put in a cost/benefit analysis and from my POV is unclear at best. There's no clear solution to avoid conflict even if we splitted to day and we had it in good terms. And I'm not even mentioning that the most probably economic outcome for Catalonia would be to suffer massively due to loosing it's status with the EU, not being anymore the preferred port for trading with Spain and basically loosing it's status as an asset for Spain.

It's natural for everyone to try to frame events in a local setting, but take in account that you are not just witnessing two ants fighting for a piece a bread, but organizations with a lot of power and resources, that actively try to shape your opinion on the issue.