Coming from my Moto X, which is apparently a weaker device with a dual-core 1.8GHz processor (don't know the make or anything, you can probably look it up if interested), I have yet to find any applications that it can't max-out graphics wise (was just playing Minecraft PE with everything maxxed). Media playback has also been super smooth. I was watching a Blu-Ray rip of a movie after first getting it (was it "Elysium"? Can't remember) and it had no difficulty at all.
I think the processing power in modern mobile devices has outpaced the actual applications. I wouldn't worry to much about the apparently "weaker" CPU. Just remove all the BS bloatware it comes with and you should be golden.
Everything you said is mostly true. Mobile ARM processes advance faster than the software devs are able to keep up.
For the last 18 months give or take, ARM processors have been in a comfortable state for most people's applications and use it.
Frankly speaking you didn't need that SnapS4 to check your Gmail or play Asphalt 8 in the 1st place, but we still got it anyways, as well as the multiple advanced models and brands to follow it.
However, it being GBATemp, I'm sure Emulation is on the minds of many, and this is where the GPU, not the CPU really matters. Its not about having the fastest processor as much as it is that the best GPUs happen to be on the fastest processors. Obviously you don't need much power for GBA, SNES, N64, or PSX, but there are still games and features in NDS and PSP emulation that can benefit from better/faster RAM+GPU. And emulation in my eyes, isn't about having your game in a playable state, but having your game never dip below 100% speed in the first place. With more power, the less things you have to sacrifice like sounds, colors, and frames, and the more you get to gain like Turbo, filters, buffers, and recording. But outside of emulating, you don't need the extra power of those premium chipsets. I can't speak for MotoX, but there are clear differences in PSP performance between different processors. Mind you software can increase emulation effeciency, but having more powerful hardware doesn't hurt.
And another thing to keep in mind of is not only a processor's battery efficiency, but the temperature as well. Another good reason to go overpowered is future-proofing. My current star of my collection is the coolest operating device I've owned, second only to Nintendo handhelds. So if you dont need the best gpu or largest screen, Moto X would be more than sufficient for 97% of the things you can throw at it.