personally i never saw the appeal in front facing speakers on a phone. if your using the speakerphone there is a good chance your doing something where you cant touch the phone or are looking right at the screen while you talk so whether your sound is at the back or bottom, you'll barely notice. if your watching something your probably using headphones or its a foot infront of you so the back or bottom position, once again, wont kill ya. if your sharing a screen with someone and watching something on a 5in screen its uncomfortable in any position sooooo back or bottom wont kill ya. its certainly not loud enuf to throw a party with. you wouldn't use it in place of your car's sound system (unless you have a beat up old 87 hooptie to which i raise the question, why do you have a phone worth more than your car?). i honestly cant think of a situation where i would need a phone with a super loud speaker(s) of the front.. now a tablet, many reasons come to mind. tell htc to put that same tech in a tablet with hardcore specs and its will sell well. *note* i'v never actually heard the m8 so im not comenting on volume or quality just position
1) Watching a video or playing a game in horizontal layout, the difference of true front stereo surround is *IMMEDIATE* and lasting. Plugged in and tipped up at a desk, it's at least not awful with htc. You can run music streams and other junk they don't like being routed thru your work computer.
2) That being said a single rear speaker can often be more practical, such as speakerphone in your shirt pocket or similar. It's not make-or-break for me but it's a big draw for htc One buyers.
with all due respect your way WAY off the mark. navigation, haveing a conversation while driving, having a conversation and you want someone else to hear. sometimes if i'm busy cooking or whatever the speaker phone comes in handy. games. youtube vids. iv'e used my friends note 3 and the s5 and the speaker use is pathetic. i'm a tile layer and use my speakers everyday while working. while some people have no use for front loud speakers a lot do.
A lot of people are using wireless speakers or stereo headsets, in fairness. Just got my father one for yard work and he couldn't care less about speakers now.