The 250 below FL100 is not really universal, for instance in germany inside class C airspace there is no speedlimit at all, most airports with more than a few RYR departures a day do have a class C airspace on top of their class D and therefore it is possible to fly highspeed without asking ATC. However, the company decided that 300 below FL100 and 250 below 5000 is enough and thats that.
You could do that TXL arrival in the 300/500 as well, however the crowd at TXL tower is not the same anymore (especially after the departure of the bear) and likes its arrivals all nice and easy with 8NM spacing on a 10 to 25 NM final, visuals are not allowed anymore, we have to practice that stuff now at greek isle airports.