It might not be in the best interests of Catalans anyway, not now at least.
- EU membership would surely be revoked, at least for some years. Loss of free trade and high tariffs being imposed.
- Multinational businesses may up and move to Valencia or Zaragoza.
- The Catalans that want to take their skills elsewhere would still be able to anywhere in Spain, as the Spanish state would still recognise them as Spanish citizens.
- Financially it could be crippling for the citizens with taxation and loss of pensions. This would almost certainly stretch to regional banks.
- Already high unemployed (especially youth unemployment, in all of Spain) would be stretched further.
Even Artur Mas recognises that Catalunya would be worse off, but patriotism holds a lot of sway.
Obviously some of these points will also affect Spain in one way or another, it would be immediately damaging for both with questionable consequences. That's one thing. If we totally ignore that and just focus on a Braveheart school of thought then there is the following issue: It should be put to a legal referendum, but honestly it's not in the immediate interests of the Catalan government because firstly they'd have to debate and plan these and a multitude of other points. Then they'd have to actually get numbers on board to support independence. The 2014 consultation had a turnout of 37% with 80% pro-independence. That's just under 30% of the electorate, not good enough. Even with all this fervour and heavy handed approach from the Spanish forces the turnout for the recent vote was 42% with 90% pro-independence, which is just under 38% of the electorate. Look at the Scottish referendum, that had an 84.6% turnout, that is legitimacy. You'd believe Catalans were falling over themselves to leave as soon as possible, but that's not the case because not everyone votes based on emotion.
Basically the Catalan government: