I agree. However, removing the sub frame isn't part of that process. You can replace the front seal after the rad and front pulleys are removed.
How much are the seals actually leaking? It's very common for the rear seal to leak a bit. A small quarter sized spot on the floor over night isn't worth the effort nor is something an inch across. If it looks like the Exxon Valdees just crash landed under your car, then you have a problem.