Some people do collect HW80s and R1s, perhaps by accident as they may have different versions for different jobs i.e. calibre, power level, length. Not everyone owns one in the UK because the 95 and the 99 are better at our reduced power limit. In the USA I would guess that not everyone owns one because they are an expensive import and they would rather buy a Chinese magnum and spend the other $300 on a decent rimfire. If I lived in the USA I would definitely have a full-power R1, just for the trigger.
I think they don't make good Collector's guns because they are a. very common and therefore not interesting as everyone has used or seen one, b. quite a dull, straightforward design, c. you want to shoot them rather than polish and admire them d. they are still in production in pretty much the same trim as they started in e. they lack the necessary quirkiness or originality that a Collectors' design requires.
Off the top of my head three rifles that are Collectors par excellence are ...
The Webley Service Mk 2 air-rifle - the superb quality, backwards facing piston, bolt action barrel seal and tang-mounted aperture sight plus interchangeable calibres makes this a Steam-Punk collector's dream! No maker will ever make another rifle like this.
The Falke 80/90 series - like a BSA Airsporter but designed and built by Mercedes. Hugely over-engineered and beautifully built with elm stocks and superb sighting systems. Rare, gorgeous and just too nice to use outside. The spiritual great-grandmother of the Air Arms ProSport.
The Park RH93 - a totally recoilless opposed-piston underlever spring gun that cocks both pistons using a bicycle chain, with a fully floating barrel and bolt-action loading system. Ingenious, top quality, slightly under-developed, very heavy but superb, and again no company will ever make one of these again.
Against these three beauties, the HW80/R1 just looks like a boring tool for efficiently knocking down tin chickens or varmints, with no more glamour or romance than a Honda Accord.
And what is life without glamour and romance?