As far as Instagram goes, I really don't care about it. It's just one more way for people I'd rather forget about from high school or whatever to find me online, lol. I prefer to store my photos on Google Plus, and really just wish that all those filters and options and stuff would be built into every phone to begin with.
I don't care about Instagram either but I understand what the problem with it is. It's not just the potential buyers who can't live without it, it's also the perception that top apps like Instagram, which most smartphone users at least heard about, isn't available. If a big app like that doesn't feel it's necessary to support WP, then many small ones won't either. at least that's the perception it creates in people's minds.
The thing is, it's very easy to solve. Microsoft paid the costs to build apps for WP7 when it was starting out. just take a million out of that 1.5 billion marketing campaign for Win8/WP8 and get that app made. it will generate more PR that the ad buy the million will be used for and will remove a road block too