Under Gravel filters can be excellent form of filtration with the addition of Powerheads capable of reverse flow.
In reverse flow, the water is pulled from the aquarium at mid depth, and forced down through the lift tube and then up through the gravel as opposed to pulling the water from below the lift tube.
Add a canister, or hang on the back filter, and water along with dissolved organics and solids forced up through the gravel in reverse flow ,,can be picked up and cleaned through the media in the canister or HOB filter.
Have used this method with large messy Cichlids and can assure you all that it works quite well.
Would agree that UGF is old school, but it can be very effective as mentioned above.
Which brings up a new topic all together! A combination of different types of filtration can be very effective, I agree. Perhaps the best method is a combined system that takes advantage of the different strengths of different types of filtration. The only snag here is how far is the fish keeper willing to go as far as budget, maintenance, and tank real estate willing to go.
Which brings me back to the point of simplicity. How complicated of a system does it really take to keep fish successfully? In all honesty a single internal, UGF, or HOB type filter will do the job in most circumstances. There really is no need to have a complicated filtration system for the average aquatic husbandman. Sure 2 or even 3 different types of filter would be more efficient, but is a system like this absolutely vital? No.
The whole point to this is that there are many different types of filtration available, each with their own strengths and weaknesses. To coin an old adage, different strokes for different folks.
I agree completely, I only took issue with your statement that modern filters are more effective.
The variation on the UGF I described is not complicated, and is much more efficient in it's application.Effiency, combined with relatively low cost as compared to some forms of filtration is often desireable for some.
As for original topic, Fish in or fishless cycle, Fishless is clearly the way for the majority but it is not to say that Fish in cannot be used with no toxic ammonia or nitrite levels,or even detectable levels,of toxins if done properly.
Daily water changes and testing with Fish in cycling, are only an issue when too many fish, too large of fish,and overfeeding of fish for particular volume of water take place.(often the norm)
Couple that with the lack of understanding of the nitrogen cycle,poor advice from others,and or inability to exercise the patience needed, and fishes are the ones that suffer.
Also to be considered are the throngs of folks that purchase fish without researching the fishes needs with respect to water parmeters (ie) pH,GH,KH,and Temperatures along with choosing suitable or unsuitable tankmates. This often results in sick or dead fish regardless of type of maturing or cycling process used.
You can in the afore mentioned instances perform fishless, or fish in cycling ,and results will be the same.
As I have mentioned,,Fishless cycling is clearly the way for new hobbyists. It gives them time to research the fishes that interest them and to hopefully select fish that will do well in the enviornment we attempt to create and there is absolutely no chance of fishes being harmed.
But as also mentioned,,if done properly,, fish in maturing or cycling, can be accomplished with zero harm to the fish. Requires very few,very small fish in proportion to the volume of water, and very sparse feeding of these few small fishes, with additional small fishes added at proper intervals and in number(s) to allow bacteria to continue to develop.
No daily testing,no frequent water changes,Just patience.
For the majority of new hobbyist's Patience is that which is most often in short supply.
I do love a good discussion! 
