Research has shown that almost half of people travelling abroad don't use the internet on their mobile phones when travelling in the EU and a quarter don't use their phones at all.
Mobile phone roaming is an obvious reminder that the EU isn't one country and the EU don't like any reminders that a United States of Europe doesn't exist (the EU Commission's vice president, Viviane Reding, has called for it again this week).
Mobile phone operators are pumping billions into upgrading infrastructure to take advantage of 4G technology and they need to recoup that cost through their customers. It costs money to provide mobile services to customers from another network and operators need to be able to charge for that service so they don't have to pass that cost on to their own customers.
All the mobile phone operators have add-ons that will allow you to use your phone in the EU and elsewhere at a reduced cost or as part of your inclusive package for a daily or monthly fee. Three allow you to use your inclusive minutes, text and data (subject to conditions) in most of the countries where they own a mobile phone network. There is also an EU cap on roaming call, text and data charges anywhere in the EU.
Consumers have options and protections, forcing mobile phone operators to create the illusion of a United States of Europe with the unilateral abolition of roaming charges is both unnecessary and counter-productive. Allow them (encourage them, even) to make their own bilateral agreements on roaming and protect the interests of their own customers.