When I started there wasn't even an Icon. Then by the end almost every npc character seemed to be a tailor.
Only trainers, really. (oh right, and tailors..... durrr... >.> )
I think the point of that was to make things quick and easy for the busloads of new and returning players that they were hoping would show up for Freedom.
For one, some folks don't have the attention span needed to travel three whole blocks to the Icon they added across the street from the Atlas hospital. Going that far out of the way is worthy of a ragequit to some players, and those kinds of people would happily exaggerate the crap out of the story. Before long they'd have had people in other games believing that the travel time required to change your costume in City of Heroes was roughly on par with taking a canoe to the moon. And when the majority of your advertising comes from word of mouth, you don't want those words to be negative.
For two, not every zone had tailors close by. Certain places were a severe fork in the rump roast to try and reach a tailor from, especially if you only wanted to do a little touchup. To help costume pieces be the biggest revenue stream they could be, they decided to make it quick and convenient to change your costume just about anywhere. Got ten minutes to
kill arrest until a teammate comes back? Why not get that new piece from the market and see if it works with your outfit? Two dollars and five minutes later, you're sporting a rocket pack and a bubble dome and you're giddy about how cool this game is, all over again.
Quick and easy are fantastic ways to get people coming back for more. Especially in a game that claims to cater to casual play; mind-numbing travel slogs eat up serious chunks of game time, which causes casual players to log out and not come back. If you only have a half hour to play that day, and it takes twenty minutes just to reach the mission door (meaning another twenty to return to the contact)... that right there means you're not playing today. But reduce that travel time to a two minute round trip, and that leaves most of your time for the good stuff.
That's how you design a casual game... the parts that don't affect gameplay itself should be simple to understand and convenient to navigate. And the parts that do affect gameplay should come in short and sweet bite-sized pieces, so you can enjoy as much or as little as you feel like that day.
It's a standard promotional tool: you're not selling the merchandise, you're selling the happiness you get from using it.