anyone: as2 vs as3?

was looking at summerLongSince's post, basic as3, and it occurred to me that the as3 version of what had been previously done using as2 was more complicated and involved (see script below). i am still relatively new to actionscripting and am currently using/learning as2, so i am ignorant to the benefits as3 has to offer at this point. could anyone tell me what benefits the as3 code below has over the as2 that precedes it? they both seem to accomplish the same goal, only as3 seems to take more time and code to do so. also, is moving to as3 worth the hassles that come with learning an entirely new scripting language? i haven't even mastered as2 and the thought of losing all the work i have put in thus far is somewhat sickening. lastly, couldn't as3's benefits have been implemented into flash without restructuring the entire programming language?

thanks in advance,
_name