I think it depends on your alliance. Mine is pretty competitive and it’s been fun going at tough defences with teams you might not normally use.
One of my favourite things is trying Off Colour Attacks. So I’ll take my blue-mono to a green tank or a Purple mono to a purple tank. If nothing else it’s good practice,
Want to try some quirky teams out? Friendly matches let you pick the weird and wacky with no risks to your main game. I want to fill a raid chest from 8 hits, anymore is inefficient so it’s rare I have spare flags for goofing around. Again, friendlies let you do this.
So for a vast amount of us this a great feature