I would never question what is such a sacred project ritual in some companies. In fact, I wish to add to this tradition in a way that may help your project succeed even more.
Generally, the T-shirt ritual seems to have developed as a way to celebrate the beginning of a new project. T-shirts seem to have clear value as a motivator to energize the new project team. I suspect it also makes it easier to recognize who is working on this new project, versus the project they just left. Watching the Olympic teams in their brightly colored uniforms recently reminded me of the emotional value of recognizing and connecting with your team (commercial value aside). T-shirts, like uniforms, make a statement.
But what we wear often serves a purpose beyond the statement it makes. Many professionals wear attire as protection. Hard hats, lab coats, and orange vests all protect professionals from the perils of their trades. So, in our project profession, I'm not sure where we got the idea that T-shirts were enough. Is it that we are still young as a profession and don't yet know what might protect us? Are we too arrogant to admit we need any protection? Let me suggest some ideas. Okay, so my tongue is in my cheek. But maybe these ideas will evoke some serious thought between your chuckles.
Topping the list for protection, a bulletproof vest comes in handy when you find yourself in the unenviable position of bearer of bad news. I myself borrowed one from an ex-cop-turned-programmer for a key meeting with the sales staff where I had to explain why their system had lousy response time. It worked very effectively at disarming them long enough to explain the dilemma in lay terms. For best results, just wear the vest under your suit jacket (Oh, does anyone wear these anymore? Okay, under a sports jacket.) and remove your jacket at the appropriate moment. You don't even have to say anything. I haven't tried it yet at a quarterly meeting with investors. If you try it, let me know how it goes.
Latex gloves are a must when de-bugging software and hardware. And please throw those gloves away when you're finished so you don't infect any other parts of the project (I'm sure they sell these in bulk). In a pinch, the popular anti-bacterial hand sanitizers will do if you don't have gloves. Of course, preventing insect infestations is even more effective but harder to sell to free-range developers used to dealing with natural pests.
Waders, preferably the style with boots built into them, are very useful when wading through project status reports full of "you-know-what." The kind with non-slip soles really helps you maintain your balance and lets you focus on catching what's important. They also let you go places in your project where you might otherwise fear to tread.
Your eyes are very important tools for seeing where your project really stands. As such, protective glasses may be necessary when reviewing project schedules and issue logs. They are even better if they magnify things like time-to-complete figures and issues you're watching for "go-live" impact. However, heavily tinted sunglasses are more stylish these days. Their primary purpose is to keep others from seeing the look in your eyes.
And of course, you may need a hat. You will have to decide which kind of hat is useful on your project. Hard hats protect you from things falling on your head and-since most of us think our brain is our most valuable project asset-this is good insurance if you are likely to be bombarded with mandates from above. Baseball caps are very "in" these days. They keep the sun out of your eyes so you can keep them on the ball (seems to work for golfers). Straw or sun hats may be all you need-just to protect you from the spotlight that may be shining on your project. And of course, there are always helmets, which may save you from head injury if and when your project takes a serious spill. There are some countries and states, which don't require helmets, citing they would interfere with personal freedom.
So now let your imagination run wild. Selecting your team's wardrobe for your next project is no small task. You may even want to review those previous project retrospectives lying around on the shelves to give you some ideas.
What type of attire does YOUR team require?