You may get a really different response from some of the parents of younger kids...but here's my reaction as the parent of a teenager. Four is very young. I've never met a parent of a teenager who wishes they'd spent more time engaged in standoffs over who would tie sneakers. And, I've spoken with many who look back and wish instead of struggling that they'd cheerfully snuggled up, said a silly rhyme and tied the shoes. Childhood is very short.
Developmental readiness is complex. It is very possible for a child to be capable of something mentally or physically but to not be ready for it emotionally. That's part of asynchrony. Any amount of pushing, even gentle, can cause kids to buckle down even further with trying new things. She may well be thinking now that she regrets every tying the shoes in the first place and may be hesitant to try the next thing if she's going to be expected to fully take over the job.
My suggestion would be to as much as you can try to allow her to have some privacy and space with her learning. For some kids who are perfectionists even the slightest hint that it matters a lot to their parent(s) feels like a HUGE amount of pressure. Obviously you aren't saying to her "you are being lazy by not reading during your independent time at night; you are a failure for not doing so; you are disappointing me." However, even just a generally nice suggestion or question about how she's spending her time may feel to her like you've said all those things.
My suggestion would be to at all times remain confident, cheerful and trust her learning process. There is nothing wrong with enjoying looking at pictures. There are adults (artists, art historians, etc.) who devote much of their attention to this kind of close observation. There are writers who are inspired to create their own stories by looking at pictures. It is a wonderful thing that she enjoys this close observation and that she's found a peaceful wind down activity before bed. If you think about it, most of us don't work on newly emerging challenging skills right before bed. I can't imagine taking on something I was just learning right before I went to sleep. My reaction to the comment about looking at pictures might be "You have so many books with great pictures. I think my favorites are the Jan Brett books, I love the way she draws animals, do you have any favorites?"
Ultimately your goal is that she's a motivated and independent learner. The best way to get to that goal is express confidence and comfort in the way she's approaching things. More space and less adult concern will give her the confidence she can try new things without fearing she will be expected to perform.
