"Dropped" is not such an accurate word here as the 「て」 is optional in the first place.
The te-form seems to enjoy a rockstar treatment in the world of Japanese-as-a-foreign-language. Learners love to talk about it, but what many rarely mention (or know about) is its informality. This is one of the things that took me by surprise when I started mingling with Japanese-learners back in college.
The 連用形{れんようけい} ("continuative form") of a verb or adjective already contains within the meaning of the 「て」 without using the 「て」.
The point I am trying to make is that the te-form is more informal than the 連用形. The te-form is heavily used in our informal, day-to-day conversations because it fits there. The general tendency, however, is that the more formal the speech, the less often the te-form is used. In novels, therefore, the te-form is used far more often in the quotes than in the prose.
A couple of examples:
「あき子はカーテンを開{あ}け、『夜の東京タワー、きれいね。』とつぶやいた。」 vs.
「あき子はカーテンを開けて、『夜の東京タワー、きれいね。』とつぶやいた。」
「つぶやく」 = "to murmur". The chances are that you will encounter the first sentence in a novel.
「とも子の瞳{ひとみ}は大きく、黒く、どこを見ているのか分{わ}からなかった。」 vs.
「とも子の瞳は大きくて、黒くて、どこを見ているのか分からなかった。」
The second sentence sounds like what you would hear in a casual chat. You would not find it in a novel, at least not in the prose part.