Re: Is caulking necessary?
AArgh! You never put tub-surround or shower tile up with mastic! Thinset mortar only. Mastic-based failures are far more prevalent than successes.
I think there is some truth to the idea that in the old days with 1 1/4" thick mud job tub surrounds, the caulk of marginal quality back then, it was a "wash".
Remember grout lets moisture in AND back out again, it's a revolving door, so caulk at the bottom is not trapping vast amounts of water because it can evaporate via alternate routes.
Remove not the ancient landmark, which your fathers have set.