Not all of us piggs are high end designer living types.. If the house it pretty ho hum in the first place a premium window upgrade job won’t make it a star or a good “investment”. I do think windows are as important. .I don’t know what kind of house the op has but he mentioned budget concerns.

I am not a fan of breaking stucco and the flashing and paper below on a 40 year old house. That paper is usually very fragile and getting a good ovelap between the old and the new gets fudged quite a bit. Not saying someone won’t do a good job, but they might not tell you if they don’t or can’t.

Some people might actually want to preserve the exterior facade for aesthetic reasons as well. In that case why rip it out if it is all sound?