Probably not seen many built cos they are old kits circa 1958 in the case of the DR.1 and have been somewhat eclipsed by the WWW Roden and CSM kits of the last decade.
I have built 5 Revell Dr.1’s over the years.
Try and find one to have a look,- you might be surprised it really is not that big, esp as the full size aircraft was quite small.
You might even find your 1/24 spad is a bit smaller than a 1/32 DH-9 and even smaller than a1/72 Staaken /Felixstowe by a fair margin.
If you had suggested a series of 1/32 biplanes just over a decade ago you probably would have been shouted down by the 1/48 1/72 afficionados as saying nobody in their right mind would pay over a hundred US for a 1/32 biplane.
Strange things markets and customers.
I remember Roden when they started up their 1/32 WWI range, about 15 years ago. People generally raved about it & more kits were demanded - I certainly have no memory of any criticism of the scale, or of being "shouted down"?
Same with WNW launching in 2010. They started with four kits, and even then there was incessant demand for whatever people wanted for their next 1/32 WNW kits. Same as today!
WNW sell - or sold - all their single seaters for less than $100, some substantially less. Even their two seaters started off well under $100.
Maybe the corollary in WWII modelling is useful. 1/24 has been around a while, but the number of kits on offer is absolutely tiny compared to 1/32, and build logs are not commonplace.
1/24 might work, but because 1/32 is already fairly large, widely available & with massive choice - including AM - at cheaper prices, I can see why people stick with 1/32, whether WWII or WWI.