Took a day to take all the tiles off the front, add insulation, membrane and batten it. Then another half day or so to put the original tiles back on

Back took slightly longer because we had some alterations done but it was just over a week in total effort

Also even if you personally don't live that long, it does affect the value. For example a 99 year lease on a property is considerably less valuable than a 999 year lease, even though very few people live more than 99 years.

Given shingles last between 20-30 years someone's got to pay the cost of re-roofing on a regular basis throughout the house's lifetime

Then you've got the added maintenance, flammability and other downsides of a shingle roof to take into account too