To claim 30mm indicates an emphasis on bomber hunting is false and just uninformed. When you look at the timelines involved and the development of the 30mm cannon, it is much more likely it was to counter the super-resilient enemy aircraft on the Soviet front. When heavily armored Fw190s couldn't dent IL-2s, you know you need bigger guns.
The 30mm was intended for single engine fighters as well. Many's the time the sturdily-built US plane soaked up tons of damage, be it P-40s over Tunisa, or be it P-47s soaking up an entire Fw190's ammo load, or what have you. The Mk103 was intended to need LESS hits to kill a target. Any target. Their main concern was younger and greener pilots as the war went on, and it was decided that stronger round meant pilots had to stay on target for lesser time, allowing for better survival of German pilots. 30mms weren't developed only for bomber hunting.
Moot: You seem to suggest there were only 2 roles in the bomber campaign: US heavies, and the planes attacking them. For any 110G of sturmbock 190 going for the bombers there were twice as many Bf109s flying high cover and escort, engaging and dogfighting the US escorts. Often far far above the heads of the bomber attackers. This was still an important part of the war. When the high-cover could dominate (or at least contend with) the US escort fighters, the bomber hunters got through and made their runs. Fact of the matter is the LW had plenty of planes they could adapt to hunt higher-alt bombers. Even if the bombers were only flying an average of 5k above B-17 or B-24 formations. Ta-152s (and in general the high alt fighter design) were there as fighters. I'm sure if they were ever to run across bombers they would have made an attack run, but so would Bf109s, or Macchi C.205s... Doesn't mean they are bomber hunters. Hell anything could technically bring down a B-17, given the right situation. Far more likely, and quite clearly, the 152, the 109k, the 109H project, and so many other high-alt emphasis was to keep up with the US side of aviation. It wasn't role-specific.
C.202s, armed with only 2x 12.7mm Breda machine guns attacked and sometimes brought down B-24s. Should you re-write history to categorize this as a bomber-hunter? Bristol Blenheims were converted to 7mm-armed night fighters, to stalk and hunt bombers at night. Should history be rewritten to categorize the Blenheim as a bomber-hunter?
I ask those rhetorical questions because that is the same logic at work for calling the 152 a bomber hunter or bomber interceptor.