Yeah, long term peace where the enemy is allowed to eliminate your men and potentially steal your resource so you have even less than what you have.
The only reason to fear the Thalmor is if you are a coward. They have NOTHING. at all. Certainly not enough men to launch a massive invasion the Empire seems to think they are capable of. The Justiciars are the only way they can crush the Empire right now.
A few men dying to keep a few thousands safe. What's your problem?
Of course it's not right, but if it wouldn't be a few who are ILLEGALLY kidnapped - this doesn't happen when the Empire is around, it's thanks to your Stormcloaks who distract the Empire from keeping their eyes on the Thalmor - it would be thousands in Cyrodiil. Skyrim and High Rock would have followed soon after. And why the heck would you want everyone to end up dead/enslaved just for your ego? Why?
They have nothing? They have what came back from Hammerfell, which wasn't that much either, but it's still an invasion force. Let's just assume for a moment that half of them returned after harassing attacks by the Alik'r warriors and thirst to some degree, could be a little more, could also be a little less, there's almost no info given.
Now, the Thalmor prepared long for their First War against the Empire, at least 70 years. They had no problems (so far) keeping their social structures internally in order, that's the easy thing about national-wide racism and rule with fear, only very few ever dare to speak against you and those can get killed off quite easily. I bet there's forced recruitment going on in there as well, on the other hand, why bother forcing it? At least the hatred and disgust for other races, especially humans, seems real (can't speak for everyone of course, but in "Rising Threat" Lathenil of Sunhold mentioned that surprisingly many Altmer
'embraced this insanity'. And they got Bosmer and Khajiit at their feet, they have everything to defend themselves and just look at the geographic factors. Invading and especially conquering Elsweyr or Valenwood is impossible with little manpower, had Titus decided to strike back they would be torn to shreds either by wild animals or Bosmer arrows, take your pick.
And Khajiit don't have fertility problems by the way. Getting manpower isn't impossible for the AD.
And just like this I rewrote what I and many others wrote to others long before you were even registered in this forum.
Do your research. Use your head; not to crash into a wall, but rather use the organ inside it.