Boss battles

Ever since I have been playing video games which must be...actually I'm not gonna say, but to keep it short a long time and there have always been boss battles.
I have always felt they are mostly placed there purely because the people who make games feel pressured to make sure it's challenging for the gamer, hoping the gamer will feel he/she has had their money worth at least.
Another reason is that maybe they made a level and felt towards the end of finishing making the level, a programmer said to the boss (possibly a water cooler conversation in most cases) "I just think the level is too easy or too short"

I think the latter would be the case with two very recent games I have played which happen to be Deus Ex Human Revolution and Gears of War 3. Now don't get me wrong both games I respect are very different and have strengths and weaknesses very different to each other, but they both share a huge weakness which I felt ruined most of the game for me which were the boss battles.

Some boss battles are brilliant that require the gamer to think outside of the box in games and are certainly not shoved there to make up for an easy or poor level. Like for example using your surroundings or timed attacks in a certain combo or technique to defeat the boss or bosses.
But Gears 3 and Dues Ex require you to fire at the person then run away, then fire at the person... and then run away...for about what feels like 5 hours which is just lazy and a cheap cop out to the game especially that Deus Ex and Gears 3 have other parts that are so good.
Like the fantastic characters and Unreal engine that is so brilliantly used in Gears 3 which brings a great tactical element to a shooter which makes the Call of Duty franchise look like it's million years behind with single and multiplayer. Then there's the new Deus Ex which I personally hated but there was some light in there like the side quests which kept me going and the augmentation upgrades which made every gamers play through unique (never mind the story decisions made in the game) for them.

But yet these clearly very talented developers choose to use cheap tactics to try and make it challenging. Nothing challenging about making someone do the same repetitive task over and over again for 5 odd hours straight, we all do that anyway and it's called a job!

Gaming is suppose to be about escapism like any other medium and it should be enjoyable, not about a task that requires ages and ages to do with no skill or a challenge for a gamer to challenge him or her.
That's what should be talked about on their break standing by the water cooler, is it fun.