[Qualifying] Is Q3 such a big advantage?

[Vettel in a Williams]

After watching Qualifying today I was disappointed (at first) to see Barrichello and both Force India's come so close yet just miss out on Q3 yet it got me to thinking....

After the last race, where we saw Webber cut his way through the field using his extra tyres to his advantage, and end up on the podium, should teams like Williams, Force India, Sauber & Torro Rosso be pushing so hard to get into Q3 or did Paul di Resta have it spot on today by only doing 1 run in Q2 and qualifying in the top end of the Q2 drop outs?

I think Paul was very clever today. After using a set of the softer tyres to get into Q2 he then saved on tyres by only doing 1 run in Q2.

I'd like to see more of this strategy from the midfield teams as it could make for a more entertaining race, especially strategy wise, if gthese teams can take more sets of brand new softer tyres into the race.