Besides his history of making blanks, and name recogniton, and cue makers that he has supplied in the past, his quality of blanks and craftsmanship is outstanding. Why wouldn't people be after his blanks is a better question.
His shop really is built around building full splice blanks, and I think he is doing his best work ever. A lot of cuemakers won't or can't build fullspliced blanks because of the waste involved and techniques used. All his blanks are built in squares in the traditional old school fashion. There is a ton of hand fitting and tricks used to achieve the end results that is best left to someone as proficient in it as he is.
I don't know why any cuemaker would be offended, frankly, converting or building on a quality made, time tested, blank of Johns. John and myself collaborate on cues all the time (Davis-Prince cues). I have been building cues for almost 20 years and I still am impressed with his work and the pains he goes through building his blanks every time I'm in his shop. He does build complete cues as well as making blanks, and does a great job on them too.
Getting a traditional full spliced John Davis blank, for a fraction of what I think they should be priced at, is a terrific way to go and the quality is, by far, worth every penny. I think that is why they are sought after, and why people choose to use his blanks.
Besides all of that, John is a great guy to deal with! He always goes above and beyond what is asked of him and has helped a lot of people along the way. You couldn't ask for a nicer, easier to deal with cuemaker than John Davis. I have been very fortunate to be able to spend quite a lot of time with him, working with him and his blanks, and I would recomend him and his blanks to anyone looking to have a full splice cue made.