P.S. The internet is great for information but once in a while you should read a book.
The two points you just made are (to my mind) and accepted and standard point of view.
Heres a summary of my opinion of the 3 key variables that affect tank choice, equipment and layout:
1. Surface area - there needs to be sufficient surface area whether due to tank shape, powerhead or air pump to create enough gaseous exchange for the number of fish in the tank. How you do this depends on tank size and the choice of equipment
2. The greater the volume, the slower any changes in water chemistry will take effect as any chemicals added (by you or by the fish i.e ammonia) will be more heavily diluted, which gives you more time to detect and respond to these changes
3. Environment - this is a pretty all encompassing area that basically means what each fish needs from the tank i.e swimming room, substrate, plants, hiding places, compatability - all these vary from fish to fish and all fish put in that tank need to be catered to. You also need to take into account the amount of biological filtration required for the various fish, depending on their total bioload.
Going back on topic, this seems like another one of Ludwigs "How long is a piece of string," questions. And the simple answer to whether to half fill the goldfish bowl is (same as the string question) :
It depends.
If you can put answers to the variables stated above in points 1, 2 and 3 then you'll have an answer to whether or not to half fill the bowl.
Ludwig, you're a good bloke but you need to stop posting stuff like this - I can't resist the temptation to jump on my soap box and state the obvious!
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