As a tabletop miniatures battle game this works great. If I don't want combat to take up the overwhelming majority of the game time there are other systems that don't feel like such a grindfest. Sliding minis around a map while carving through the mountains of hit points do not make the combat more engaging for me.
Spells should be named for what they do. The sleep spell should be called lethargy, because its very easy to cast this thing and have NOTHING fall asleep. Confusion? The only thing confusing about that spell is why it carries that name. Psychic damage and mind control..........well I'm confused.
As far as feeling heroic goes, my character feels a bit less heroic if he stands a chance of dying of old age before dropping a couple of kobolds.
So, you have a horrible DM, or you are playing through Keep and haven't hit 2nd level yet.
That's a flaw of KoTS, or the general concept of a themed adventure where you have recurring villains ... you fight similar monsters over and over again.
As for sleep ... what did those types of effects do in 3e? I believe it was EITHER nothing at all [save] or something really cool [knocked them out].
In 4e, it does something automatically, and if you both hit and they fail their save, then it does something cool.
[Note: Save ends was the replacement of the 1d4 rounds type of effects from 3.5 ... while save ends means that over half he time, assuming no penalties, the effect will end after a turn, there are ways to impose penalties, etc]
Judging the game based on a combination of the first half of the pre-release adventure and evaluating the theoretical effect of spells [how often have you seen/used the spells that are so dreadful] isn't going to give you a good view of things.
I am playing in Scales of War, while running players through the H modules [were past half way in H-2]. Things get more exciting, even in the H books. It's not all kobolds all the time. And honestly, I doubt any encounter lasted more than 6 rounds, if that. The rounds might take a bit longer, but this is entirely based on the people involved ... if people have to look up powers, hmm and haw about what to do, where to move, etc ... it can make it SEEM like it's going longer. And without one-hit kill spells [although there are always minions

] it's going to take a few shots to bring people down, especially brutes and soldiers. Concentration of fire does a LOT to kill off "mountains of hit points". Similarly, I've seen the monsters concentrate their fire and take down fighters and paladins in a single round.
As you level you are constantly getting new stuff to do, and opportunities to swap out powers if you want to try other stuff.
And ultimately ... the WOTC adventure books are dungeon crawls. This doesn't necessarily mean that DMs can't make their own campaigns ... but ultimately, most pre-made adventures are going to be grinds. Judging the system by the pre-made adventures is a bit unfair. It's something you should bring up to your DM, and see if he, or someone else, can come up with a campaign that isn't a dungeon crawl.
[For DDI Subscribers, they put up a second part to the Gladiator article, outlining a bunch of skill challenges and other things that could be used for a campaign, or at least adventure, where the PCs become involved with gladiator games. Here, not only are you fighting, but trying to get the crowd on your side, build up you reputation, etc].
It's not so much about the damage dealt but rather the amount of damage that has to be dealt. Heroism is about getting to do things that fighting a couple kobolds all day prevent you from doing.
20 rounds of fighting Kobolds is 2 minutes in game terms. The rest after the fight with the kobolds is going to be longer than the fight itself, and even 10 minutes out of the day isn't much.
Ultimately, your basically saying that fighting kobolds isn't heroic. It didn't USED to be heroic, because they would barely hit, and had so few hit points they were basicaly minions. Kobolds in 3.5 were jokes. In 4e, they are threats, albeit low level ones.
If they were easy to kill and "get on with your day" then odds are they wouldn't need adventurers to deal with the threat, they wouldn't be considered menaces to a town. They would be seen as nuisances, the way you seem to consider them, based in part by how they were represented in 3.5.
And, ultimately, it is only the BEGINNING of your heroic career where you deal with kobolds, there are other monstrous races higher up the ladder, not to mention undead and various beasts, etc, etc, etc.
If you see the fights in 4e as nuisances that arise while you are attempting heroic work, than the ending of the nuisance isn't heroic. Of course, it completely ignores the fact that those kobolds, left unchecked would proceed to do what kobolds do ... and those eaten babies would be on your hands. Killing kobolds = saving babies. Is saving babies unheroic?