They are preparing the U5 Upgrade in order to have more options for future builds and also to leave the cave at some point. You might also have noticed, that all rooms are already at max level. So this might be a thing to expand everything later. Beside, the dev deliver every month updates and hotfixes in a short time if something messed up.
I agree with you, that you could build up your army pretty fast. Sometimes I start completly from scratch just to enjoy the game. Still funny, because If you have bioasshard for example, people complain about less Sex animations every Update and more RE game with stupid riddles. Here is the opposite the case.