I don't agree. They deliberately and effectively built-up Fett in Empire Strikes Back, and he wasn't just an "interesting costume".

I don't think you understand or appreciate why Boba Fett got the reception he did from fans. Yes, of course the costume had something to do with it, but that was just a part that played into the way they portrayed him.

Think of the movie Empire Strikes Back. Much of that movie was basically building up how resourceful and capable that Han Solo was. It also built up how strong and ruthess Vader and the Empire were.

So when Han outsmarts the Empire and Vader finally turns to the bounty hunters, he seems to know Fett's repuation already. Big plus for the audience's perception of him. And now we know that Fett has a reputation for just killing/distintegrating his bounties. So now we know he's ruthless.

So Han outsmarts the Empire again (floating off with the trash)...but that doesn't fool Fett. +1 in the audience eyes again. Respected, ruthless, and apparently good at what he does.

Then we see Vader breaking deals with Lando and threatening him, but when Fett complains that Han might die in the carbon freezing Vader doesn't threaten him or break the deal--he says he'll be compensated. So again Fett is shown respect by Vader.

All this is done to build up Fett, and was deliberately done economically in terms of on-screen time. But why bother to build up Fett? Because they had built up Han Solo, and you can't have Han defeated by a nobody unless you're shit at storytelling (Fett was the counter to Han the way Vader was the counter to Luke. Underworld vs underworld and Force vs Force.) The fact that they did it with so little on-screen time makes Fett more of a mystery, and this is where his armor also comes in. He's as faceless as a stormtrooper, but for him it enhances his mystery because we know so little about him. When we know so little but see him so capable and getting so much respect, we fill in the blanks mentally. That is a really effective way to build up a character. It's the same principle that made the alien in Alien so effective: we got glimpses of what it could do, but actually saw very little of it, so we filled in the blanks.

And that is also the danger of a show like BoBF. Once you start to demystify a legend/myth, some of the magic is lost. The mental constructs we had about him get replaced, and many are bound to disappoint. The same thing happened to many people with Darth Vader. The more we got to learn about Anakin from the prequels, the more Vader lost a lot of his mystery and didn't seem as special anymore. And don't even get me started about tyhe Force being demystified with the Midichlorians explanation.