Well, we recently had an encounter that started when our archer ranger was scouting ahead and was spotted by an enemy. He was down before we reached him and it took the combined effort of our two leaders and a couple of healing potions to save him. After the encounter he was down to one surge. So he pleaded for taking an extended rest.
However, nobody else wanted to, since except for him, nobody had lost more than a single surge. We convinced him to continue by pointing out that our leaders also had ways of surgeless healing. So we had another two encounters before taking that extended rest (although he refused to do any more scouting

).
I think that was the closest we have come to a '15 minutes adventuring day' in 4e.
Ha - what a wuss!
Our ranger once entered a fight with no surges left and only one hit point. Mind you, that was on an occasion before a safe local rest site had been found, but the player did have to put up with comments like "don't leave the minion too exposed!"...
As a general rule, I agree with the view that the 5MWD is not a huge issue in 4E - that has been my experience, too. Nevertheless I do feel that, in the cost-benefit analysis that must be done comparing the benefits of moving on with the benefits of finding a site to rest and getting a full healup, the scales are weighed a little too much in favour of the extended rest, on the whole.
There are two ways to address this perceived problem (and if you don't perceive the problem then there's no reason you should address it at all - but finding reasons the party can't rest right now is
not "not addressing the problem", it's just
one way of addressing the problem).
Option one is to reduce the benefit of an extended rest. I have done this in some cases: when in particularly harsh surroundings in-game, I have set Extended Rests as only partially effective, on a "recharge" principle. Surges and Daily Powers are rolled for in a way similar to monsters' recharge powers - i.e. needing X+ on a d6 to get them back (the value of X depends on how bad conditions are). In practice, for surges at least, you can use a "law of averages" for the bulk of the recovery - if X is 4 then just get back half of all expended surges; roll for any odd ones. This method works fine sometimes, but it isn't always justifiable or fun.
The other option is to give a bit more reward for pushing on. This can be fun; a carrot is usually better than a stick. It doesn't need to be much - Action Points, Daily Item Power uses (which I still use for the more powerful Item Dailies) and added item abilities (especially for rings) already give some incentive. These are mostly just ways to stand still, though - a little bit more would be welcome. The Escalation Die idea comes closest, for me, to what might be ideal.