I should explain the player attrition point a bit better. Given weekly matches, in order to avoid serious injury, and give players a chance to get over general wear and tear the team will need to be rotated to a degree. So it is not that, we are encouraging player attrition, but rather seeking to avoid it, that gives us, the benefit of a broader team selection.
De-powering England IMHO does not make Ireland or the 6 Nations, as a competition, stronger. Why are Aus generally a a lot better than Ireland given their similar player numbers and Union is their 4th sport as well? They have 2 RWC wins and have been final losers twice on other occasions. Playing BNZ/SA regularly is obviously the answer, i.e. regular exposure to high quality matches. Ire could be the northern hemisphere Aus sandwiched btwn Eng & Fra.
Eng & Fra are the 2 behemoths of world rugby in terms of player numbers and finance. Neither punches their weight at RWC level, principally due to their lack of a pyramid system with the national team on top. Therefore, condensing the 6N might give Eng some help, but it doesn't cure the fundamental issue that sees them under-perform at International level.
I realise the lack of a few fallow wknds would make Ire's job harder and probably impacts results negatively, but anything that makes the 6 Nations better preparation for RWC's is good for Ire IMO. An acceptable trade off for me, I can understand it not being every Irish fan's opinion though.