That excerpt was awfully wordy, and almost the opposite of "concise".
I feel as if this piece of text could be edited and condensed into a short paragraph, and that could be it. That feeling might turn out to be wrong.
I don't know - I really wouldn't want them to add these to the game in such a half-hearted manner. Companion characters are a very tricky element to add to a game. They can easily cause any number of problems - overshadowing the PCs, unbalancing the fights, slowing down combats, distracting players. Tossing them in with less mechanical support for balancing their stats, or with less advice on how to use them and what to be careful of, seems a recipe for disaster.
Sabotaging newer DMs for the sake of a little extra space seems to be exactly what the 4E DMGs are trying to get away from. They can afford to explain things thoroughly and go into detail. I can't see any decent rules or advice that would come from summarizing that entry into a single "short paragraph" - what is it you would cut out to get it 'down to size'? I'm genuinely curious here, because I don't see too much that could easily be trimmed.
The paragraph giving examples of companion characters in the genre?
The paragraphs and bullet points cautioning about the potential dangers of adding in a character?
The paragraph about the problems they can solve?
The advice on allowing the PCs some input, but keeping it primarily within the DMs hands?
The rules and advice on actually constructing the character to fit a balanced role in the party?
I don't see any of that as out of place, or any part that could easily be removed to make it more 'concise'. I mean, maybe you could trim down one paragraph overall, but any more than that, and you start losing actual advice and material.
The thing to keep in mind is that these rules are mainly for making combat relevant NPCs - figures that actually adventure along side you and help accomplish your goals. If all you need is a simple 'henchman', sure, you probably don't need something this extensive. But adding in a character is a complicated enough task, with a strong enough impact on combat, that doing so without solid guidelines would have a negative impact on a lot of games, and hardly worth saving that extra page or two of text in the book.