The creator of Naruto, Masashi Kishimoto, developed a world with a lot of potential and cemented the series as a cultural phenomenon that has reached people everywhere. However, there is also a lot of criticism about Kishimoto not being able to fulfill this potential and this is shown through several characters such as Neji Nyuga, Rock Lee, Gaara, Shino Aburame, and, of course, Tenten.
Tenten has become a running meme in the series because of how little the creator of Naruto has used her and how she was often viewed as a running joke because she didn't have special ninjutsu abilities, although there is more to that than meets the eye.
Disclaimer: This article contains spoilers for Naruto.
The creator of Naruto misused weapons specialist Tenten
Tenten is a ninja from Naruto's generation and a member of Team 3 (also known as Team Guy because of their sensei, Might Guy), featuring her, Neji Hyuga, and Rock Lee. They were a year older than the rest of the generation because Guy wanted them to be ready for the Chunin Exam.
While Neji and Lee had their moments to shine in this arc, the reality is that they were underutilized, and that applies tenfold to Tenten. She is a weapons specialist, capable of summoning multiple weapons in mere seconds, and a girl that was capable of holding her own in Team 3, which is impressive considering Guy's extremely high standards and his demanding training.
Out of all the Genin in the Chunin Exam arc, she was the only one that never had a moment in the spotlight. Her fight with Temari, while fun in some instances, was anime filler and wasn't a part of the manga, therefore taking that away from her.
The running issues with the creator of Naruto
Masashi Kishimoto, the creator of Naruto, is a writer with very clear virtues (great at backstories, crafting villains, coming up with ideas, and portraying emotional moments) but his flaws are even clearer. He is very inconsistent with characterization, tends to ignore a lot of great characters, has way too much focus on the Uchiha, and does not know how to write female characters.
Tenten is an example of many of these trends. She is a ninja with abilities suited for that role and creative battles but she is never given a chance to grow. A lot of readers or viewers might argue that her abilities are not good enough for the series' power scale, but that was by design and the writer can come up with ideas to make it work, just like he gave many power-ups to Naruto and Sasuke out of nowhere, for example.
It is also interesting that she is one of the few female characters whose entire motivation is not centered around men. While the likes of Ino and Sakura were fawning over Sasuke, Tenten stated that she just wanted to be a strong ninja for herself, which was a refreshing perspective in the series. Considering she was part of the second most prominent team in the series, it feels like a massive disappointment by the creator of Naruto.
Masashi Kishimoto is the creator of Naruto, one of the most successful franchises of all time, so his not using Tenten to her full potential is not something that would impact him much. However, Tenten, much like Neji, Rock Lee, Gaara, and many more, is an example of having a character with a lot of potential and squandering it, which, looking at the series now, feels like a waste.
Naruto, at the end of the day, was a successful series that could have been a lot better if other characters, clans, and villages were given more time in the spotlight, resulting in a lot more diversity and creativity from the author's part. Tenten's misuse can be a very good extrapolation of that argument.