Downvoters: show us your links.
Hmm, still not sure what USB connectivity the OP thinks is missing:
24bit 192 Khz DACs for iDevices:
SD card reader and USB host:
http://www.amazon.co.uk/High-Quality-digital-Connection-connector/dp/B00AXC5MBW/ref=pd_cp_computers_3 5in1 digital Camera Connection Kit USB/SD/TF Card Reader For iPad - £5.99
High quality headphones with iDevice remote controls and microphones:
High quality microphones for iDevices:
There may be valid complaints about the iPad, but being unable to connect stuff to it is not one of them. True, the USB host isn't built in, nor is a microUSB port, but then they aren't on the Samsung Tab, either. The Nexus 7 requires an adaptor to be USB host, and the Nexus 4 won't support it at all.