If it's your first trip to Universal, but you are familiar with Disney - you have to keep the "convenient/inconvenient" comments in perspective. What might be inconvenient to those of us that are Universal vets, would be considered extremely convenient by Disney standards. It is certainly more convenient to eat at one of the many great restaurant options inside the parks. Having said that, it's not exactly inconvenient to eat lunch at City Walk.
You can head to the park in the morning, get a full (by Disney standards) day's worth of rides in before lunch, eat at City Walk for lunch, go to the hotel to swim then head back to the park for almost another "day's worth" of rides before closing time.
It might be a 20 min (???) walk from Men In Black or Diagon Alley to City Walk - and 10 minutes to get from City Walk back to a park entrance after lunch. It is only because at Universal that 30 minutes translates to 2 or 3 rides that anyone would consider it "inconvenient" or a significant delay. For a Disney vet, it would be considered extremely convenient.