This comes up every so often. Regarding multi-use, I, for one, wouldn't want to command a crew that had sidearm/tricorder/communicators somewhere on their persons at all times -- especially since, in TOS at least, landing parties are so often separated from their communicators. Hopefully there is gun control in the 23rd and 24th centuries.
And remember that we view it all on TV in 2-D. For all we know, bridge viewscreens and tricorders offer 3-D imaging. And communicators have Dolby surround!
Anyway, when someone invents a cell phone that is able to transmit my coordinates down to the molecule, via "subspace," so that my body can be converted to energy for transport, without towers or satellites, and we have hand-held ray guns that can stun or vaporize, that combine handheld computers (in a pinch with some vacuum tubes and platinum) which can scan and deliver newspaper clippings from alternate timelines centuries ago, which can also scan spaceships in orbit from the ground, then yes, all Trek devices will be anchronistic.