> Roaming is relatively niche
From the EU's perspective that was a problem, limiting 2 of 4 aspects in the single market's stated goal of free movement of goods, services, people and capital, namely services and people.
Services are still somewhat limited (you can't just buy the Latvian 15€/month service as a German in Germany, telcos made sure of that), but given the reliance of contemporary folks on connectivity, it helps somewhat on the "free movement of people" bit.
> net effect will be: poor people who do not use roaming (e.g. because they cannot afford vacations abroad)
There's a contingent in European's poor (from Eastern Europe) that works abroad (Western Europe) and benefits from not having to deal with roaming anymore.
(also, from my experience from when I was poor[0], it can be ridiculously cheap to have a few days of international vacation within the EU)
[0] poor being relative, but I think most official metrics would have covered me.