The top hat and tails actually started with Kellar, memory serving me right, and was properly adopted by Thurston who was the David Copperfield of his day -- a good looking younger gent that the tail look simply accentuated charm and pizazz around.
Our evolution away from this classic look can be credited to one specific individual more than any other source; Mark Wilson and his success with early television. While he wasn't the only one hitting the Tv market in a modern styled suit & tie style, he was the one that was most seen by the public and the one that inspired the majority of magicians of that particular generation -- my generation. BUT, I was on the outer fringes of that Baby Boomer era and found greater influence by way of Doug Henning and to some degree, Copperfield during the 70s, neither of whom were known for Tux, Tails or even Ties.
Long before Blaine and whatshisname guys like Kevin James, Franz Harary, and even Rudy Koby were changing the look of the stage magician towards the Glam-Rock look of the 80s. They were likewise introducing a greater sense of the macabre (especially Kevin) along with a number of others, few of whom anyone know of today (outside that big mouth from Massachusetts, perhaps). Punk Rock was one side some took, which slowly evolved into Goth back when Goth was real and not just costumed facade a.k.a. Hot Topic Goth (huge differences). From this scene most of those that had moved through said evolution found themselves moving into the now popular Steampunk look and fantasy style . . . . that is to say, those that are keeping up with trends, some folks out there are a bit behind the times.
Even with all this evolution in which things change at least every decade if not faster, there has been one long set standard when it comes to getting the higher paying jobs -- the classic late 20th century suit & tie. Until you become a "name" and a genuine "star" showing up at a corporate meeting dressed like whatshisname or one of his many clones or any form of "costume" simply isn't wise. They can willingly buy a character that goes with an act but I've seen situations where they want the persona tuned down a bit due to the company's conservatism.
Another thing that must be considered as we look at this question is where we perform. David Blaine's first special in 97 was a deliberate kick in the nuts for Copperfield; an odd looking/acting kid with less than a $200.00 investment in props, devastated David's marketability over night. There was a new form of magic being demanded by the general public. The bridge between Copperfield styled magic and what Blaine presented was Angel and in his earlier days as an evolving public personality, he was quite awesome in how he'd refashioned the world of grand illusion. Sadly, success blinded him as it does many and like others, he's stopped evolving as a character. He's no longer "novel" in that there are 1001 KIDS out there trying to mimic his look and antics. . . and if you haven't noticed, most of we older guys consider everyone wearing white face & mascara to be an Angel clone even though a great number of these people aren't stage performers but for some reason believe that the street corner is akin to legit commercial work. Sorry, but in my day that simply wasn't the case even though I've worked plenty of lines over the years outside clubs, so I understand the visibility side of things and getting exposure.
Today there are some new shifts happening, such as the Urban Shaman trend that's been percolating over the past few years; a strange organic direction that's more Pagan in look & style -- a storyteller that makes magic "real" but not necessarily someone that's tied to the bizarre side of magic, which is where we typically find this kind of thing. These performers work with very simple effects, few of which take on the familiarity of say, the Cups & Balls but more akin to Geller's famed Spouting Seedling or a color changing leaf. Where this concept evolves to I haven't a clue, but I do like it; it's a wonderful melding of sidewalk entertainer, the traveling bard, and true pagan perspective.
Magic today and the clothing worn, is mulch-faceted and depends strongly on the venue and market one is targeting. More and more "costumed" persona exist now than we've seen in well over 100 years, possibly more (a lot more), but the business suit still reigns on high, as the "proper" attire for the present day showman.
