Some folks say "just write and you will get better". Well, no. If we just write with no foundation, we write crap. I know because I did it, and I thought my crap was fantastic. Thankfully my writing has improved by leaps and bounds. The secret? Reading books about writing.
"No, we can't go to the park." "But why?" "Because I said so." That never worked, did it? It doesn't work on readers either. If our stories can't pass the Why Test, there is a motivation problem. The problem may be even deeper than why we allow something to happen, or a character to act a certain way. Is the part/person in question justifiable?
It's your baby, and you're letting somebody else tell you what they like and don't like about it. Who does that to their children? The same people who know they must "kill your darlings". Thank you Stephen King for telling us how it is. For many, beta readers are a must. For some, they are a waste of time. You get to decide!