What was your biggest issue with the Nintendo Wii?

[Never]

A great console.
The number of quality games seems to be often underrated by people who only bought it for Mario, Zelda and wii sports.

My Issue's with the Wii are:-

Motion Control:
Motion control has it's place, and sometimes I love it, but they should have packaged a regular controller along side the wii mote as standard for games that are best without motion control.

Lack of HD:
My biggest issue is resolution. After HD tv's became the norm Wii games started to look really bad. Maybe I could forgive the resolution if it could handle decent AA on all games.

Lack of big name games towards the end of the systems life:
In 2010 and 2011 wii gaming were largely about a selective collection of quality niche games (I don't play the shovelware). You could still have good times on the system, and you were missing out if you were one of those who let it collect dust, but all the big name games were elsewhere.

To many the system was dead by then. And unfortunately that's an understandable point of view and the slow death of the wii is one of the big reasons the Wii U now suffers.