The whole concept of the Frankenwatch is one of those philosophical conundrums (conundra?) to me, and there seems to be two distinct categories of them.
First of all there are the attempts to retain a degree of authenticity, where a bunch of components sourced from every corner has been assembled into a working watch that resembles as closely as possible what would have come out of the factory.
Where attempts are made to pass this off as "factory original" it is simply out and out fraud, but when it is quite clear that it is a "bitsa" the ethics become a bit cloudy. I read an article once about a chap who had assembled his own Omega Speedmaster moon watch chrono entirely from spare parts. All of the parts (dial, case, movement, bracelet, the lot) were NOS factory original Omega parts and correct for the particular model. It just wasn't assembled by Omega and had no serial numbers on the case, bridges, or main plate.
So just how much less of an Omega was it compared to "the real thing"? And if it is any less, then if you have "the real thing" serviced (stripped down to component level and then reassembled) by an independent watchmaker (ie. not Omega), does that then lose any of its authenticity?
To me, the only crime in this category of Frankenwatch is in trying to pass the thing off as factory built if it wasn't, or trying to pass off combinations of components, or components from different manufacturers, as factory original. So long as you know what it is, the watch is fine.
The second category isn't really Frankenwatch at all but is more "rescue" watch, where an un-cased movement and dial has been re-homed in a new case.
There are so many of these orphaned movements around these days as precious metal cases are salvaged (vandalised) for bullion, and these are increasingly turning up in modern stainless steel cases. Some of them are very well done too, and provided it is clear that they they are not original pieces, is there anything wrong with that? (other than the destroying the original in the first place).
Redials are a whole other can of worms. My take is that I would rather wear a watch with a good quality redial that I can read, than struggle with an original that has become so patinated as to make it indecipherable; and since I believe that the primary reason for having a watch is to be able to tell the time, the watch that can be read has more value than the one that has to be squinted at in good light. The argument that the redial is not as it was when the watch left the factory, but the original is unaltered, is nonsense. If the original has any sign of patina or discolouration then it has been altered by time itself and the environment that it has lived in.
As for welding strap lugs onto a pocket watch, well that's just odd ;-)