In socialism/communism you will still have personal possessions, would you want to use someone else's underpants or toothbrush when you could go to the store and get some for free?

Possession is the key, in the former USSR ownership notionally resided in 'the people' but control of the means of production resided in a bureaucratic elite. As it does in state-owned enterprises in the UK and USA, most of the means of production took the form of capital as they do in private hands in the west. The USSR also used money to allocate resources on an ability-to-pay basis (capitalist not socialist), without democratic control of production (capitalist not socialist) and produced for profit (capitalist not socialist).

Technology (the forces of production) is so advanced that we can now feed, clothe, shelter, communicate with and entertain everybody on the planet without the need for anyone to go without or work their nuts off - it's time for the next revolution. IMNSHO