The problem with conversions is that the term encompasses a wide range of guitars. Converting a trashed junior into a special makes sense, juniors are plentiful and Specials are becoming more and more expensive. BUT they are the same basic construction, the wood between the two is exactly the same, you're talking about some extra routing and cosmetics. They are all slab-bodied 50s Les Pauls.
Same with GT to burst conversions (or P90 to PAF), it's a change in routing and cosmetics, not the actual construction of the instruments (well, sometimes neck angle). They are still all carved top 50s Les Pauls. The Burst is the king of electric guitars and conversions have been around for 40 years now, they are not a new phenomenon. There are more of them being done nowadays but the bulk seem to be otherwise trashed guitars finally being fixed properly and rebuilt into their ultimate version. And that's 'ultimate version' as the market dictates - they get turned into Burst conversions because that's where the market it at, pure and simple. I don't think anyone in their right mind would take an otherwise straight GT and hack it up to make a Burst, at least I'd hope not.
Where I draw the line though is with the guitar in the original post. Juniors into Bursts are a nonsense imo. The construction is so inherently different that there's as much new wood as old. You have to change the guitar entirely to turn it into something it's never been. And because of that they should be (but often aren't) priced far below GT conversions. I see them as no different to replica's frankly.
I myself own a conversion - a 1956 Les Paul Custom converted to PAFs. It was converted when I bought it and it remains my number one guitar, it is a stellar musical instrument. Conversions remain the best way to get into a real 1950s carved top Les Paul with PAFs but they aren't all created equal.
I can see why folks do conversions but I'm not a fan for Junior/Specials converted to standard per the neck set difference? I'd only consider a GT conversion as a quality choice for a platform but I'm sure the old growth wood in that 54 made for a good sound. I'd have to guess that Lays reset the neck on the 54 at the start since they are so shallow originally.
Why can't people accept the fact that if they can't afford a burst, then they just can't have a burst?? Period.
And, please don't tell me conversions fill a gap in the market.
What market? A market of people who think they're entitled to get that tone for a fraction of the cost so they'll do anything including destroy pieces of Gibson history?