Are historical furniture manufacturers anti-vintage?  

Here's some of the possible reasons:
Most of the HW furniture listed in books and that I've seen for sale reminds me more of the late 1930's furniture (Robjohn-Gibbins, Rhohde, etc). They usually had that glossy amber finish that's not quite as 'organic' or severe as the lightly finished, more natural wood finished pieces Knoll and Herman Miller produced.
Also, Heywood-Wakefield furniture were (apparently) not designed by any known designer, I've never heard of anyone attributed to being responsible.
Maybe it's just me, but i tend to think of Heywood-Wakefield as being part of the "Grand Rapids Modern" middle-quality stuff and not as high on the great quality pyramid (I may be wrong, but the fact that their pieces don't fetch high prices, would seem to indicate that others feel the way I do).
You know, Heywood-Wakefield reminds me more of Conant-Ball.

Newsflash! "Anti-Vintage" is the average mindset
Among low-level employees who work for mass-market furniture manufacturers, it's surely the norm. Use your imagination to filter your query through the ears of the sales rep you spoke to.
He/she probably lives in a small town somewhere, and is most likely unaware of the fact that her employer's products from 50 years ago now enjoy a cult following. He/she probably has never even heard the phrase "cult following", for that matter.
Is it really so surprising that this sales rep suggested that you buy a NEW bed, when you inquired about obtaining a new part for your 55 year old bed?
Your phone call was probably fodder for jokes in the break room, for the rest of the day.

hw
There were quite a few lines of Heywood Wakefield designed by fairly well known designers. As far as them not caring, yes that's the typical mindset of most people but it might also have something to do with the fact that Heywood Wakefield isn't owned or run by the same people anymore. I think HW even went out of business and then was resurrected by these new people but I could be wrong

You can't
generalize the issue based on one example. Some companies, and some individuals, are aware of and interested in promoting the history of a company. Other companies and individuals are not. Surely you can expect today's reps to sell today's product; there is no inherent incentive to promote yesterday's line, unless there is a perceived value in helping a potential customer with any problem related to the company.
No, H-W is not for everybody, nor is it the typical post-war Modern we usually cover here. It might be seen as a "soft" pre-war modern, suitable perhaps for a warmer architectural environment (Cliff May, H H Harris, Wm Wurster), or else the typical pre-war apartment or post-war ranch house.
What do others think ?

Artek is PRO-Vintage
Artek is now offering vintage pieces for purchase, alongside new pieces. To me, this is a brilliant idea, that as far as I know, no other manufacturer has done. It taps into the "green" market, creates awareness and strengthens the historical legacy of their brand, and broadens their demographic to include vintage collectors.
"Because of Alvar Aalto and Artek's legacy, and more specifically their wide distribution of home and commercial furniture in the 1930?s - Artek, with Tom Dixon's leadership, is re-collecting and re-issuing the old pieces (from old factories, shipyards, even flea markets) and introducing them as a new line of beautifully aged pieces. We love the idea that as a consumer, you could buy something "new" to you, that is already embedded with such a rich history and design legacy. Hats off to Artek and Mr. Dixon for pushing the envelope on recycled and sustainable design initiatives. "
Full article, click link below:
http://www.inhabitat.com/2007/06/13/artek-and-tom-dixons-2nd-cycle-furni...

"i tend to think of Heywood-W...
"i tend to think of Heywood-Wakefield as being part of the "Grand Rapids Modern" middle-quality stuff"
Don't get "quality" confused with "desirable." HW is indeed high quality in construction IMHO. Most pieces you find are as sturdy and rigid as the day they were made. Now - because they weren't designed by a super highbrow well known designers (or at least in the instances they were, they certainly weren't marketed as such) - does not imply anything about the "quality" of the pieces.
HW, as mentioned before, was certainly not ahead of the curve. They could be defined as "modern-light" by some. And like mentioned - they were a decade or two behind - more like 30s modern. BUT - they are well made, and in my opinion, attractive in small doses. I especially like the dining tables (with other chairs).
They were the among the first companies, if not the first, to produce some eames pieces. Of course, this was short lived, and virtually unknown.