The thing about the match to me is, watching it, I believe that Scotland had it in them to hold the lead if they wanted to. The bonus point system, if you ask me, is why England won. The match was not at all about winning or losing in those final minutes. Scotland were up 12-9 but playing like they were down by 4 (which they "effectively" were because of needing to win by more than 7 to advance).
Had that not been a factor, Scotland would have been playing to hold on to the lead starting from about when it was 12-6. They would not have been taking chances late in the game with the lead, and I think they would have held on for the win.
There are a couple of key things, one of which you have highlighted, but for me over the years it has come down to two things:
We panic when in the lead in the last few minutes.
The players lack the confidence to either close out the game, or comeback and win it.
Scotland vs. Italy 2008- 20-23 last minute drop by Italy secures win
Scotland vs. Argentina 2008- 15-21 after leading 15-10 well into the second half
Scotland vs. South Africa 2008- 10-14 after leading 10-0 at half time, Godman misses penalty from right in front of the posts.
Scotland vs. Argentina 2009- 6-9 last few minutes drop goal, dominated match
Scotland vs. Wales 2010- 24-31 after leading by two scores in 70th minute
Scotland vs. Argentina 2011- 13-12 after leading 12-6 72nd minute
Scotland vs. England 2011- 16-12 after leading 12-9 75th minute
All these were games we were well in top in, should have but ultimately lost in those last 10 minutes or so going back to 2008. Games which our immediate 'comparables', Ireland and Wales, most likely wouldn't have lost.
Meh, I think it is just more hurtful to say the English deserve credit than to say we are sh*te