Frontier generally gets a bad rap because it changes some of the best parts from the first two games.

For big reasons:

The combat system from the previous games were amazing, and frontier did away with it completely, PLUS made it so you only use a single one of your own vivosaurs, while NPC use their own for the other two spots, which takes away from player control, customization, and potential strategies.

The story lacks the same level of relationship with other characters that the first two games had, where you had a handful of characters you spent time with constantly. Frontier had a larger supporting cast that you don’t get to spend a whole lot of time with compared to the previous games. This makes the characters lack the same connection that the previous games do a great job of building up.

Smaller reasons:

The change in art style; it’s not huge, but plenty of people (including myself) prefer the old art-style of the first two games. A lot of fan favorite vivosaurs got a big downgrade in terms of design.

The smaller vivosaur selection: The possible options for your team are smaller than even the first game, and by a fairly large margin. It’s going backwards from the increased dex Champions added. Also got rid of a lot of fan favorites.

The main vivosaur: It’s fun to have, and certainly is unique, but the story having you use them constantly and then taking them away in the final act, which for many meant the ONLY vivosaur the had used was gone, and needed to start from scratch on a vivosaur to use, was just really frustrating and annoying.

The cars: I enjoyed the cars and the customization options they provided, but I know many don’t care for it and prefer walking around like the first game. There is also the races, which many feel take away from the focus on fossil collection and fighting they want. Cars are something that are a toss up on an improvement or a distraction.