Why do you say this? It doesn't seem to make any sense to me to have it restricted like this.
I don't have a developer quote confirming 100% that it's WAD. But it almost certainly is, because:
- It's a one-line text file change, the most trivial of fixes, that could have been changed easily in 1.2 or 1.3 if it was indeed a bug.
- It is consistent with the majority of other CBs - most CBs require a border, especially the powerful ones.
- It's consistent with the overall design of the game: requiring slow, steady progress with an emphasis on borders; e.g. most CBs as I mentioned, restrictions on coring, selling provinces, Fabricate Claims.
- Curia Controller is already awesome with its bonuses and neighbouring-required excomm and Crusade CBs. It would be OP if these CBs did not require that.
I realise it makes no historical sense; but many mechanics in the game don't, and that's fine with me. It is in any case consistent with the rest of the game in gameplay/strategy terms.
I used to dislike it, as others here do, but I'm now starting to quite like such restrictions. It requires more planning and strategy when you have to take certain territory first, which might itself require taking certain other territory first, and so on. You can't just get Curia and spam CBs across the other side of the world, you have to build up to a position where you can use it. It requires more thought. More sub-plans in your master-plan.
And besides, all you're missing without a border is the CB. You get the Crusade bonuses whenever you're at war with the target, whatever CB (or no CB) you used to DOW.
So, worst case, send them a loan for them to renege on, then DOW with that CB. Then enjoy the lovely bonuses. Perhaps even mix this crusade war with other wars, and enjoy the smooth, refreshing taste of Crusade bonuses on all.
Remember to drink your Crusade bonuses responsibly.