Q:

Is using the term "Legos" always wrong? 

LEGO tries very hard to protect its brand name.  There is a company policy to use the expression "Lego bricks" rather than "Legos." 
I am fortunate to live close to a Legoland and a LEGO retail store.  However, I occasionally hear an employee say "Legos," and of course the (American) public uses "Legos" all the time. 
Is this incorrect?  Are we just being lazy? 

A:

You can say "Legos" if you want to.  But for The LEGO Group it's an important matter, because if people start saying "Legos" about similar products produced by other companies, LEGO might lose their brand if it is deemed genericized. 