You’re not offending anyone. But as you have admitted you are a student, and I assume a student with little to no real world experience. Many of the people who have provided feedback to you have 25+ years experience in the field, including myself.
Depending on the client, depending on the client’s brand and depending on the purpose of the piece you are designing there “may” be some personal artistic expression involved. Such as for example producing something for say a skateboarding company, or maybe Nike or even Coke. But even in those instances (especially coke) you’ll still have some brand constraints that you must work within.
But you also need to keep in mind that graphic design touches a huge amount of what we see and interact with in the world. Every product on the shelves, every website you visit, every app on your phone. Some better then others. And in many of those instances companies have curated an overall brand style both in their look and feel, their brand voice. their brand colors. And as a designer, you need to work within those brands to communicate the brand image they want to portray, and in some cases it is clean cut and corporate (take banks or hospitals for example), in some cases it may be more elegant and refined (luxury goods and services) and in some cases they tap into a more artistic and playful expression (such as some lifestyle brands or potentially brands geared towards young adults.)
And yes, there is an art to designing and designing well, even producing more clean and corporate work such as for a bank or hospital. But it isn’t art in the sense of fine art and personal expression.
Sure, you could focus on just clients that are more geared towards personal expression, but even then they generally are at the whim of who they are working for. So, you might create something you personally feel is great and is expressive and is art in your eyes, but they may come back to you and say, change this or change that, or can you incorporate more of this, or we need you too use more of our primary brand colors. Because at the end of the day you are being paid and commissioned to produce something for the company that is paying you.
Graphic design is not fine art. It is re-enforcing and expressing a company’s brand to their customers in order to drive their business and generally to increase sales and revenue.
Perhaps pursuing a career as an illustrator would allow you more of a chance to be more personally expressive in your own personal art style, but now a days illustrators have many obstacles, and it is challenging to rise to the top where you would be a sought after commodity.