Errr...no? The company, AFAIK,
prefers "Lego bricks", which is much like "Lego brand bricks". "Lego" is a brand name, but the items themselves are simply "bricks", "minifigs" etc. This policy obviously exists to protect the trademark. Otherwise they might lose it like happened to Hoover vacuum cleaners, nowadays "hoovers".
That does not make "Lego" a mass noun, or even a common noun in the first place. They don't want it, because then it wouldn't be a fully protected trademark or a proper name any more. The only Lego you can buy is the whole product line, which will cost a few billions. A single brick is not a "Lego" with a capital L. It's a brick. Two bricks can be called "two Lego bricks" but not "two Lego" or "two Legos".
That's the official company policy. However, what people end up doing in real life is simply a matter of common speech and evolution of language. If "a lego" (with a lower case l) becomes a common noun (like "to google" became a verb), its plural can be anything. The easiest solution is to call them "legos", just like multiple vacuum cleaners are "hoovers".
If you want to disagree, please provide a link. Uninformed fanboy ramblings don't count.
Fascinating things these elder signs, I say.