Please let me share a bit of my limited knowledge particularly in marketing, Sir.
Aside from mechanical issues such as durability etc, I found that Donic has too much product line for their blade --> Dotecs, Burns, Sensos, Player named blades, Epoxs, Bloodwoods and some ungrouped blades (Cayman, Combi, etc)..
Aside from the rather high price, there is soo much choice and it has been researched that people has less tendency to buy the more varied the product of the same use is..
Combined with the generalized review issued by the vendor (usually written on the back of the rubber packet) and rather inaccurate reviews on the internet (such as TTdb which is usually biased because of the lack of info aka what product is used together with the reviewed item) makes it hard for one to make a decision.
Aside from some people who love to try out stuffs (so called equipment junkers with of course enough provision on their pocket), trying out blades is not a viable option for those who want a stable game and equipment. People can't just buy stuffs while they have no idea how it will play for them and whether it will be used continuously in the end.
Probably it is the same reason some rubber brand was discontinued while some much less varied and tested-by-time product such as The Srivers (FX & EL, not the G2 and G3), The Mark Vs (Classic and AD, the other? Not as much..), The 729s (Classic, FX, 2000 Tack Speed), The Hurricanes (Classic, Neo, Skyline) etc still has high demand on the market..
Slightly off-topic, we have one bread brand in Indonesia which is very successful, it's called Roti Boy. Roti Boy's product is a simple butter-filled coffee bread, now selling worldwide..
That is my opinion and rather detailed view about why Dotec seems to have little love from players
Yosua