Why? I never played the first and I still loved the game. Sure you're missing a bit of story but other than that you don't gain anything from playing the first.
You sure do, you miss the biggest part of ME2, the huge feeling of dissappointment simply won't be available to you if you've not played ME1 first
Its actually a game I'd almost consider recommending you play ME2 before 1 as its just better on every level.
Combats a bit more realistic, but its dumbed down, easier, with incredibly narrow weapon choice and less abilities while in battle.
Me1 is a brilliant game, a touch slow at first but EPIC story and locations throughout. Boring as crap resources, but thats only worse in the second game, honestly I wouldn't be against recommending you just use a trainer and give yourself a decent wedge of cash as you go into the game, most of the time in ME1 its not money limiting you but weapons become available as and when you level up and do things so having a gazillion to spend straight off won't make much difference. The second game even more so, theres nothing to buy yet resource stuff is more boring.
I'd also potentially say give Dragon's age another go. I did like ME1 right through, and ME2(its ONLY a let down because of the first one), but I got Dragon's age essentially as a birthday present last year, installed it, played, crashed, played, crashed got bored, hated the combat, hated the feel, hated it though I did like the story/characters/dialogue.
I tried several times to get beyond the intro and the first village and finally did it a week ago and have been playing almost non stop. When you get a better spread of characters, only a couple of levels and a bit more understanding of how to set everyone up it becomes far more enjoyable to the point where I'm having fun blasting people in various ways with a very diverse mage.
I think its one of the most offputting(gameplay, not story/dialogue) intro's to a game in years, the first 3-4 hours are even maybe horrible to play, the intro locations are dull, the first battles are dull and need WAY to much management, but after that its plain sailing and a very good story, great characters, good locations, etc, etc.
The only thing still there, a year later, is a silly amount of unresolved crashing, though that seems to go hand in hand with most of the best RPG's these days.
EDIT:- Worth noting first few times I tried a champion and rogue and I still wouldn't recommend them, tanks/champion types tend to just get stuck in and run out of stamina while running all the "come hit me instead of Mr Squishy" skills. Meantime you pause every 3 seconds to get the mage with 30 different options to do the right thing. Playing as a mage as I am now reverses that, the boring guy basically repeatedly taunting does that effective with no control, the mage, I can do a ridiculous amount of different things very quickly without all the micromanagement.
I really did HATE the combat at first, I can't stress that enough, I thought it was truly awful and just couldn't stick with it. Now I think the game is great, though there are some major problems, tooltips from the stone ages, it is still very hard to know what spells are worthwhile and which aren't, a lot of luck got me a pretty damn good build, though you could always look one up.
Its really worth a go, lol, just realised this is all a complete waste if you actually finished it, but I assumed you didn't. If you hated it as much as I did at first I can't imagine coming even close to finishing it as its way to long to play something you hate.
Its just pew pew and having people whinge at you. Nothing will ever top KoTOR I'm afraid. 
