personally, I don't feel we should sow or plant anything out into the wild unless it is of local provenance. Although many garden species are relatively harmless, others are rampantly destructive and by the time you have worked out which is which the rampant ones have taken over. I don't think its worth the gamble of introducing yet another nasty.
Actually if I had my way all gardens would mostly native species too!
When I dug a new bed I went out seed collecting in the wild and planted them in the bed - as a consequence I have birds foot trefoil, wild carrot and St John's wort popping up amongst the flowers and fruit shrubs, all pretty and all better than a perlagonium or some shrub imported from New Zealand.
I would have thought also that wildlife benefits better from the wild plants it has evolved alongside rather than what we deem to be useful to them.... Nettles may be ugly but just stop and have a look for a while and you'll see they are stuffed full of life.
Also, all the wonderful people that I have loved and lost in my life go everywhere with me in my thoughts and memories and I don't need things to walk past to help me remember them - but I know grief affects different folks in different ways. - but affecting your local wild areas in a potentially negative manner for all time doesn't seem that great a choice but I suppose many wouldn't realise it was potentially damaging
