There has been a lot of discussion about the mounting for the T4s (and the T8s) when they were first introduced. Do a search here in the forum for "T4s Mount" -- that will get you about 22 other discussions and solutions on this subject.
The T1 included a mounting system for the then-current L1 Classic, Model 1, Model II, and Model 1s to integrate to the cylindrical radiators. They also offered a mic stand mount that some folks had great success with, others not so much (some felt it was too easily prone to breakage.) Personally, I was always afraid of tipping the mic stand, especially when the weight of a boom, the T1, and all the cables (and my own klutziness.)
When the L1 Compact was introduced, the columns were plastic, and I believe Bose didn't feel comfortable with its ability to hold the T1 reliably -- so they avoided liability altogether by not including any column mounting system. When the new mixers were introduced, the 1/4" tripod mount provided a "universal" connection to a readily available stable mount. (Also, the T8s is nearly twice as heavy.)
I have seen third-party mounts, including arms, trays, mic stand thread to 1/4" adapters, and homemade gadgets. At least the T4s has a reliable, strong mounting lug when a lot of other small-format mixers don't have one at all!
I have an IK Multimedia iKlip 3 iPad Music Stand Adaptor. The spring-loaded clamp grabs onto the sides of the mixer (I use T1's) and holds it securely. $50.