Even with the iPad, the specs are on par with the iPhone. Neither devices are properly capable of managing that amount of tabs whilst simultaneously running other apps and processes without sacrificing performance, even though Apple's 'magical' multitasking management may help improve it's efficiency. An 8 tab limit is just arbitrary - the dynamic memory and multi-tasking management will be more efficient in determining the optimum amount of tabs it can handle at a particular time.
Throwing in some capable, beefy hardware never is and was Apple's style as we've all seen. They're more into efficiency and bettering user experience than anything else (whether you think iOS is better than Android is down to personal preference).
Compare Apple's idevices with those running Android and others, Apple's hardware is way behind the competition in terms of raw specs. However, compare the way Apple's devices handle processes, it's generally more efficient and faster in many areas over it's rivals, even with it's reduced-spec hardware. It's not all about paper specs, the software has to be optimised to use that power efficiently. If you want 2gb of RAM and a quad core processor you may have a longer wait than you think because Apple won't include it that easily.