AS3 has become very popular because of speed, functionality, object-orientedness, effects, bla bla bla. Stuff that cannot be obtained using Actionscript 2 and I understand why... And it feels like Java/C++ and stuff... another reason why it is bloody popular.
But I, as well as a lot of other old-school AS programmers, have actually found a way to make flash games using the old AS2 so-called "sissy" and non-standard methods and have succeeded in doing them fast.
In the end, it all comes down to:
1- what you have to create,
2- how usable and cool the product you want to create is
3- how fast you need to create it
With Actionscript 2, I can do wonders. Basically the 3 points above. With Actionscript 3, I can do even more wonders. But with the expense of number 3. I have to be frank. I am NOT a programming expert. But how did I manage to come up with all my flash games? Many sleepless nights? Time sacrifice? But I have no idea. But I have done it all with Actionscript 2.
Actionscript 3 maybe powerful and maybe able to create lots of effects for the web but 90% of those AS3 lovers who claim to be able to create "special AS3 stuff" are all... let's say... "small-time programmers" who are either part of a development team or who are coders who code small applications with cool effects. Yes, they can spend a week coding a cool 3D effect with AS3 and say AS3 is so cool cause it can let me do this. But what can they do with the cool 3D effect? Sell it?
I, as well as some others like me, am different. You see, I need to make games. Working games. Games with a main menu, different modes, storyline, animation... And I gotta do them all by myself. So, strangely, putting code on buttons and timeline really speed up my work. I can make 5 main menus in a day. But in AS3, I need to use event listeners, create classes... just for buttons. You can argue: Well, it won't take much but when you need to do lots of stuff and fast, you will feel it. I am not stating this from my assumptions. I HAVE done event listeners too, and after comparison, putting codes on buttons are a lot faster. And the classes, packages... ooh... They are a big step forward and can do many things too, I know, but I can do the same output without them, and faster, using AS2, so why need them? You can store data of RPG game characters using classes, but I have successfully used the simple AS2 built-in objects class aka new Object() to do the trick and create an AS2 relational database and I have successfully built a whole strategy game using that. If I were to use AS3 to do so, I will surely encounter lots of problems and errors during compilation. Sure I can try and fix them, and get it to work but then again, game development speed is a huge factor to me.
I remember that some guy said AS2 is just for a fat 13-year-old kid making hentai flash adventure games... well at least he finished making a FULL game. And let me tell you this: hentai flash adventure games are 10-times more popular than a cool 3D AS3 effect. Unless you are able to come up with a cool 3D AS3 game but I be once you are done, the fat kid would have come up with 9 more popular hentai flash adventure games... hehehe. I myself have been using the "sissy" way of putting codes on buttons for as long as I know and I have created lots of full games that are far better than hentai flash games. Noticeably a "season mode" in my game Aevarrian Coliseum 2.
I have found lots of negativity regarding Actionscript 2 once Actionscript 3 is released. Examples are: putting code on buttons are for sissies, and AS2 will be extinct and you will be extinct with it... But the way I see it, we just gotta use what we need. If all we need is AS2 and AS2 can get you to what you want FAST, AS2 sissy button codes would be a good choice. If you wanna do some flash game with millions of particles floating around and you need to beat the Flash Player lag, or create non-lagging 3D stuff, then you have to use AS3.
I will always remember that the true reason for creating flash games is for the players. No matter how cool your AS3 3D effects and functions are, if the whole flash is not usable (due to poor design or browser/flashplayer incompatibility issues) or not at all fun at all, or you took too much time to come up with it (sapping away your time and cash reserves) it will still be a failure. But if your flash game is not so advanced, and using AS2, without functions available only to AS3, but it is real fun to play and can gain a big fat wave of popularity and can be created in less time, you will definitely benefit more. This is my case. People will not care what script you used to make the flash game/application. People only care what the game can give them in terms of usability and fun and awesomeness, and how fast you can create new games for them. Based on this, you gotta decide what Script to use : AS2 or AS3.
To conclude, I am not saying AS3 is bad. It is the future and it is the bomb! There is no reason for plainly saying AS2 is crap just because AS3 is better. And even though AS3 is not as hard and difficult to learn as some others claim, AS3 is certainly a script that would increase flash development time by 20% to 400% in certain circumstances. And if in those circumstances, the development time extension is beneficial to the end-product, then it is good. Otherwise, AS2 will be the savior. I know that AS3 will be spreading like crazy but I really hope AS2 will still be available for use forever.