I think Commodore made the right decision: Tapes were a thing of the past back then, even for the C64. They made sense in the early 80's, early 90's people didn't want to use tapes anymore. For modern C64 use, the only room I see for datasettes is to digitalize tapes for preservation purposes.
And because the Mega65 recreates the C65, not the C64, I don't think it should have a tape port either. That it is possible as an add-on is bonus. It may sound a bit blunt, but with these things anything adds to the cost and making the right trade-off what is supported and what not is key to success.
Modern use of the tape port usually involves datasette emulators. Emulation is not ruled out at all if no physical port is present.