While I'm a fan of using extremes to test the bounds of an idea, sometimes we get a little apples-to-oranges. In my experience with stuff like this, I've started looking more at specific output and intended purpose for things, rather than what may be the 'pinnacle' of design or and idea.
A 2.5L engine making 500hp is impressive; call it 200hp per liter. While that number on a street going vehicle would pop eyeballs 50 years ago (turbos be ****ed), that is well within the design envelope for a lot of open deck engines. Comparing anything to an NHRA Top Fuel engine is lunacy... those engines are making over 1200hp/liter on a conservative estimate (some would say 1400hp).
I certainly wouldn't go out of my way to close the deck on a 2.3 motor unless it was the limiting factor... and I don't see that happening for any reasonable person, or the majority of people who are slightly unreasonable for that matter. Triumph's engine designers likely didn't close the deck for any sort of performance/reliability gains... these days it's usually about the most cost effective way to achieve the design goals, taking into account parts and services as well as manufacture and possible warrantee. Everything about the "jug cylinder" configuration over the individual sleeve set-up screams easier to assemble, easier to service, and more profitable to sell as replacement parts.
Just my opinion, of course