I think the screw heads are a red herring. The screwdriver costs next to nothing, it's really not a problem spending a few dollars on tools for a phone that comes apart well. I think there are much more relevant things to complain about as far as actual "serviceability" goes.
The reality is, if you aren't the kind of person who can spend a few minutes researching and procuring the correct set of screwdrivers, you really should not be opening the case anyway. If you've ever opened up an iPhone and for example replaced the battery I think you would agree, the pentalobe screws are just the appropriate level of deterrent. Crucially, there's no DRM on the battery preventing me from swapping it out myself.
The iphone 4 originally shipped with regular phillips head screws on the outside, but Apple quietly switched those out to the pentalobe head screws sometime after the initial batches of phones came out.
The reality is, if you aren't the kind of person who can spend a few minutes researching and procuring the correct set of screwdrivers, you really should not be opening the case anyway. If you've ever opened up an iPhone and for example replaced the battery I think you would agree, the pentalobe screws are just the appropriate level of deterrent. Crucially, there's no DRM on the battery preventing me from swapping it out myself.