This page notes details of 4-Starred Ladybug of Doom (WIND/Insect/Flip monster/Effect Monster) : decks, tips, effect and rulings. Learn and enjoy playing Yu-Gi-Oh! Duel Links!
Two reasons why you can run it. One: There are still plenty of level 4s (Fire Kings, Hammer Shark). Two: WEEVIL. I cannot tell you how mad I get when I use Jade Insect Whistle and the opponent slaps a 4-star Ladybug down on top.
lol trust me, Level 4 is the most common and most important level in Yugioh, especially once we have Xyz.
Not to mention, even now, we actually have an increased number of important Level 4 in the game. Destiny Hero Anki deck for example, runs 3 different Level 4 monsters.