This is pure speculation and a bit presumptuous. Perhaps some vocal critics will feel this way but I would welcome inert gas purging if Televue decided to offer it. It’s just not high on my list of astronomical eyepiece qualities though.
Right, and if TV had introduced N2 purged eyepieces first, they would have been hailed as the greatest thing since sliced bread.
This. And other companies following the good example would be blamed for copying, lack of ingenuity (because they didn't do it first) and generally be laughed upon, because they didn't offer N2 purged waterproof eyepieces before TeleVue.
I surely don't see it as a sales gimmick. It's a genuinely useful feature in some situations and certain climes, for others, it's not an important thing, just as with so many other design parameters. Some are important to you, others not. Choose what you need.
It is a useful feature so I too would not call it a gimmick. That said ES has chosen to market and highlight this as an important feature…just look at their advertising.
Very clever on their part, clone your competitor’s eyepiece yet offer a useful feature that they don’t offer. Market it heavily on that feature and even make sure that the outside of the eyepiece mentions the feature. If you look at binoculars nitrogen purging isn’t often a feature for astronomical binoculars but it is for high quality birding/terrestrial type binoculars. These are binoculars that are used in all kinds of weather conditions including rain. Most of the times the feature will be mentioned in the description of the binoculars but they don’t usually advertise it on the outside of the instrument. That’s the difference between a company like ES and say Zeiss who nitrogen purges many of their binoculars.