At least for my wife and I, the practical conversations all came before, by the time I proposed, we were already both in agreement about how we would handle finances, kids, etc. The actually proposal absolutely should be romantic, because it’s not “I have suddenly decided we will marry, we’ll figure it out from here” it’s “I’m now ready to take the big step in going from planning to spend our lives together, to actually committing to do it”
There’s plenty of room for both romance and practicality, and having a romantic proposal certainly doesn’t exclude having practical sober conversations before hand