[wpm]

I pay $200 a year ($17 a month) for access to a large, productive portion of VMWare's datacenter stack through VMUG. 6x that for access to a social media API is a terrible deal. At $100/mo, Twitter is basically saying "We don't want your business".

[tracker1]

That is more likely the case here. They don't see profit from their side to make lower level access between the free and $100/mo tier as worth it... and would rather see corporate backed developers who are likely to have 5+ figure annual contracts than deal with tens of thousands of $10-20/mo subscribers disproportionally using the system.