You are proposing that a ship that can enter High Sec and jump to Cynos that don’t appear on the overview should be able to haul volumes of cargo rivaling that of the Blockade Runner. The built for purpose cloaky hauler.
The hangar you are proposing that BLOPS should have can carry anything and they’re unaffected by fittings so this isn’t a case of fitting a Blops with cargo expanders to carry that frigate. Either it can carry the frigate or it can’t.
Also yes, BLOPS do get used to move cargo, though generally people just use them to jump a Blockade Runner rather than cynoing the Blops itself, but it depends on the volume of cargo you’re moving. For small volumes Blops-jumps, no matter which method you use, are one of the safest methods of moving goods in the game.
Because the ships are supposed to be range limited by their fuel capacity. If they wanted them to be able to carry stupid amounts of fuel they would have given them a stupidly large fuel bay.
Fitting and flying a ship in Eve is about decisions and tradeoffs. Not having every potentially convenient thing readily available and at your fingertips.
“Content” isn’t just code for more stuff blowing up, it has to involve restrictions and limitations on what you can do too, and that includes the potential to run yourself out of fuel because you jumped too far. Case and point, Jump Fatigue. There is actually a direct and noticeable increase in both kills and deaths by capital ships that followed shortly after Jump Fatigue was introduced, which can be largely attributed to the increased feeling of safety making people more willing to risk the ships.