Castles take a 9x9 chunk of land (with the castle in the center). All the area around 67,74 is blue already, except for another 10 tiles. A castle out in the middle of the white area will gain 81 tiles. The incremental gain @ 67,74 is just too low to be worthwhile. Since we have limited resources, and castles are a potential security risk (if taken over) we should be aiming to get the most land gain per castle.
I was planning to stick one @ 60,77 anyway, which will grab all the same land your one would, plus heaps more. I'd still have to put one there even if you build @ 67,74, so you're castle will effectively gain 0 tiles. Why don't you build the one @ 60,77 instead? That will permanently take out the most of that area as possible.
BTW, nobody should ever bother with "claim land" at all! it's a completely useless waste of time! A castle permanently claims 9x9 land within minutes of being built, whereas the 1 square claims revert to neutral over a few days, so you have to keep going back to refill them. And we're going to put a castle over those places anyway, making manual land claims a complete waste of effort.
~~~
To people requesting lots of money for quests like taking over cities and stuff: the money doesn't exist so I couldn't put those quests through if I wanted to. I'm also not inclined to spend my limited money paying people to stick garrisons in silly places too. If you stick a garrison on one of those blue locations, I'll be glad to build a castle on top for free though. It's probably cheaper for me to do that since high level character build faster/cheaper, and I have a level 10 Construction skill character.
Or, I can help out by attacking city guards to make conquest easier. But I don't have time to play the dungeon part of the game so there's no revenue stream to pay 10K gold for people to take over a city or placing a tower. You get a city out of it: that's the reward, you don't need extra. Kingdom taxes bring in a few thousand a day, it's not a lot. I get more loot from wandering around collecting my garrison's loot from monsters.