The answer is Kleenex. Now try to tell someone in a general conversation that you when you're talking about Kleenex, you meant 1) the actual company Kleenex, not the 2) product nor the 3) other generic tissue paper products. Because now you have to explain to consumers why your Kleenex is better than your competitors Kleenex, when before you could just say 'Kleenex, the brand that works' or 'Kleenex, the brand you trust' or just plain 'Kleenex'. Even if it's just a name, if you reduce the number of ways for you to differentiate your product from others, it just makes it harder to do so.
I understand the confusion (here in the South Eastern US they use 'coke' instead of 'soda' as the generic term) but are there other ways for businesses to react? It seems kind of silly to fight against a brand name being subsumed into colloquial speech by frantically suing the pants off of everyone. And when the term finally becomes more widely known as a generic term instead of a brand, then what do you do? It doesn't make sense for "realator" or "entreprenur" to be trademarked. So what should the organizations that own these trademarks do? Hang on to them in desparation? How does that benefit anybody?
See? That's how well these companies did with their marketing. It was such a successful campaign that you, who I'll presume is an intelligent human being, see it as silly legal issue. Frankly speaking? No. There really isn't another way for businesses to handle it. You're talking about legal issues, and the way to resolve legal issues is through legal means.
It seems silly now, but to many of these companies, it's the way for them to be unique, to stand out among the crowd. Because they came up with the word 'realtor' and 'entreprenur' to describe themselves, not to describe others. And, rightly or wrongly in this case, the government said that the words they use to describe themselves was so unique that it was worth it to legally make it theirs.
(And all the past successes of these names being turned into generic terms (Kleenex, Xerox, Aspirin) is the other reason why these companies are fighting tooth and nail to make sure it doesn't happen to them. The government has basically stated that it's a use it or lose it situation. And they are determined not to lose it. Whether or not that's a good thing....)
The answer is Kleenex. Now try to tell someone in a general conversation that you when you're talking about Kleenex, you meant 1) the actual company Kleenex, not the 2) product nor the 3) other generic tissue paper products. Because now you have to explain to consumers why your Kleenex is better than your competitors Kleenex, when before you could just say 'Kleenex, the brand that works' or 'Kleenex, the brand you trust' or just plain 'Kleenex'. Even if it's just a name, if you reduce the number of ways for you to differentiate your product from others, it just makes it harder to do so.