why add a dual core CPU to a device when it's not needed for number of reasons.
1. OS is not optimized for multiple cores and this includes Android too.
Rubbish. Modern versions of android use dual core processors well. Even older versions handle it adequately.
2. It's only going to push the cost of hardware up for OEM's and will result in more expensive phone for consumers.
You want the best, you pay. Price will be half what it started out as after 6 months anyway.
3. The more cores, the more battery the phone is going to suck.
MORE rubbish. Dual core processors use LESS power than single cores due to optimization in the data pipeline and intelligent handling of halt states, etc. For example, the Samsung Galaxy SII lasts at least a day longer than does the S1, making it one of the best performing battery savers out there - it is also the most impressive of ANY smartphone available today.
Oh, and furthermore: you claim android needs 'task killers'; not only is this outright WRONG, but it is also firmly recommended AGAINST using them. That they are available in the android market means nothing more than poetry books also being available there.
Anyway: I respectfully invite you to stop talking crap to people making serious requests for information. Take your fan-boyism away. Thanks. Feels better already.