If I had to guess, I'd say most of the concerts you've been to were not in the last ten years. I'd also like to say that your entire idea about what kinds of bands should have what types of shirts is completely backwards. For the most part, the more obscure low billing bands playing small venues, particularly indie bands, are much more likely to have merch like this not the big bands.
Well known bands usually have very loud dead weasels with a lot of text promoting whatever national or world tour they happen to be on much like the cowbell shirt. The smaller bands currently depend a lot more on a dedicated fanbase and tend to go the route of a simple more artistic design that often has nothing to do with the band itself and the band name. There is room for both. You can hot tamale and moan about how, "lol dis is sum jamba juicezzzz der" but you really have no idea what you're talking about.