why do tripod heads lag behind cameras? Or is it strategic?

I have LONG been looking and reading, searching for an eventual replacement for my surprisingly long-lived and reliable SLIK tripod. I really only need a new head, but would like a new tripod as well so my old one will act as a light backup. It's an old aluminium model with a pan-tilt-swivel head for photography. I need a video head for shooting quality video - as does anyone with a modern camera that now wants to shoot good video (of which most cameras are more than capable)

Our choices? Buy another head for video only, and continually swap back and forth; remember to carry both with you. Because the video head you buy will not allow the camera to flop over for portraits. I've heard this degree of freedom called "swivel" (as opposed to pan and tilt). And a pan-tilt-swivel head will not operate smoothly for video like a fluid head.

There are, of course two ways around this. Use a quick release plate design that is square so you can remount your camera sideways on the video head, and then tilt all the way down for portrait shots. But almost none of the quick release plates are square, certainly not any of the widely available ones, or those that adhere to an attempt at standardization. Many can't buy into such a system because they already have quantities of expensive equipment that demands some other plate design. The whole nonstandardization of QR plates is a whole other topic of frustration for us all. Paying outrageous prices for certain popular systems isn't an option for everyone and these systems don't have square plates!

the other solution is an L bracket that has to be carried everywhere or live on the camera. OK, it's possible, though a bit annoying.

What I can't figure out is why the obvious solution simply doesn't seem to exist! Why do tripod/head manufacturers everywhere go on and on insisting that the world is made of three things: pan-tilt-swivel heads, ball-heads, and fluid heads for video. Ball heads as far as I have heard are hated by video shooters because once you losen the ball, the camera is prone to flop over and maintaining a level horizon is virtually impossible.

Why on earth can't a fluid head have a simple tipping (sorry - I'll keep to the term "swiveling") top mounting plate so a camera can tip over to the portrait orientation? Are tripod manufacturers unaware that nearly all modern cameras can now shoot video and that MANY people out there shooting video are doing so with cameras that can also shoot stills? This seems to be lost on those manufacturers, unless I've overlooked their solution.

If their solution is for everyone to simply buy two heads, then one would think a competitor would quickly spot the hole in the market and fill it.  Honestly, it isn't a mystery that popular products are those that people really want and need. If a camera can now do two things, why can't a tripod head made for the camera?!

Or have I missed the obvious solution? Does everyone really carry 2 heads around with them, have a square mounting plate or an L plate?

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Scott G