now would pools jump to 2mb where there might be hit by that bug AND say 5 other propagation issues aswell all in one swoop of mega F*ck-ups and then have to tear up and remake a 1mb block with half as many tx's to try again..
or wrongly guess that it must be an issue at 2mb so try 1.9mb and have that block too throwing a tantrum in the orphanage, then try 1.8 and so on all creating orphan tantrums trying to find a new 'sweetspot' that is acceptable(to potential knitpicker: yes i know bitcoin doesnt have an actual 'orphanage' place, im just entertaining wordplay of 'orphan drama' to entertain the imaginations of people with short attention span)
Are you saying that the network participants should put *trust* into the miners in hopes that they don't centralize in order to reduce orphans, but rather produce smaller blocks?

This thing might have been answered several times but still I cannot understand why do we need a hardfork when softfork is available,
We don't.
aside from that, is it really necessary that a hardfork is needed In order to upgrade bitcoin features?
No. Well, some things can't be done with a soft fork but there aren't any planned hard forks that 'upgrade' existing or add new features.