As is the same with the original RP2, block placer shouldn't move when attached frame moves. With this function, we can make frame-place-and-move structure easily

This is by design. Its not intended to work exactly the same as RP2. There is a workaround, you just need to figure it out :)

One way is to use another frame motor to move the block placer back into position, but that seems perversely complicated. Has anyone found a more elegant way?

Man is right. I just hit the same problem. I used to do a very long elevators on redpower 2. When u build skyscraper from the lvl of the sea 63 block, up to max possible blocks position u need a long elevator. U can't use a stick go under the ground since it eventually will hit a bedrock. Redpower 2 solve this problem very easy. I thought project red was meant to continue redpower. I don't see a particular reason why block placer shouldn't be "immune" to a frame. At least from a block place side. Other side is ok, but wat the possible use of construction to put a block placer face to a frame that will drug it? Please do at least some sort of patch that will fix this issue. Would be very appreciated.

One way is to use another frame motor to move the block placer back into position, but that seems perversely complicated. Has anyone found a more elegant way?

Thought it would fix my problem but it's not. In my case block placer rip up from it's place and go with elevator. On the bottom there is a block breaker so i need to constantly move block placer back down with frame. That means i need to repeat placing frames on another frame motor. Which lead us to problem where we started from.