Neville Chaimberlin Lo Mes,
�Someone who seeks out a public wifi, downloads stuff, then looks at it later has already surrendered to his yetzer hara. He has nobody to blame but himself at that point, not his phone. That�s way too many steps to still blame the phone.�
I don�t think you are being realistic about the nature of temptation. If a device has a capability to do something, there will be times when a temptation exists to use that capability.
Your original argument posited that there was no difference between a glass slab touchscreen and a flip phone, so long as their functionality was the same, and thus the community�s preference for flip phones is a �minhag shtus� if a glass slab was cheaper. My contention is that the flip form factor is an additional �step� � as you put it � to guard against phone addiction or inappropriate usage, and maybe that�s why the form factor is preferred by segments of our community, including the OP�s parents. I made two points to support my contention: 1. the interface of a glass slab touchscreen is designed to promote more usage (yourself excepted), and 2. Extensive filtering and restricting of a device to remove most of what it was designed to do is likely to be a less successful solution than getting a device that was designed to do only a few functions and needs little to no filtering.
I�m struggling to understand your objection to these two points (setting aside the pricing argument) beyond your first statement that you personally find a touchscreen slab hard to use. Some of your arguments seem to echo the anti-filtering MO viewpoint of �smartphones are fine and people should just behave themselves�. But you seem to be pro filtering, and understand its necessity as a guardrail in our ruchniyus to at least some degree. So what exactly are you disagreeing with at this juncture?