With all the mongrel VTs (no offense to VTs or their fans) out there the market is already filled with unknown lines. At the end of the day, it all comes down to what the breeder wants to do. If s/he wants to breed VTs then that's up to them, but it takes the same amount of time, money and effort to breed nice looking fish than to breed ugly ones. Raising 100 VT fry will be the same as raising 100 HM fry, except the latter is nicer to look at and sells for much more.
I myself haven't bred fighters yet but the ones I plan to spawn (when I get rid of those cursed platies, PM me for free platies) will be from what looks to be good delta/super delta lines.