OP, you're still in "new mommy" mode. You want to spend all your time with your little baby girl, and don't understand (yet!) why some people WANT their kids in bed early every night. Trust me, give it a year or two. Parenting is stressful! Babies are E-A-S-Y (even the difficult ones are cake compared to when they become toddlers...). There will come a day when you WISH your kid was on a schedule, and you will be back here posting "how do you get your kids to go to sleep early???"
I cannot tell you how many parents wistfully say to me "you are so lucky your kids go to bed early; I wish mine did!"
My kids bedtime is between 7 and 8 (we're flexible enough to allow for some wiggle room). There is no negotiation. They are 4 and 5 years old. They WOULD stay up until all hours, if I let them, but when bedtime rolls around, we do baths and put them in their beds and they are ALWAYS asleep within 15-20 min, tops. They sleep approx. 11 hours per night. This has been our "routine" since our kids were each about 4 months old. It was OUR decision. And, I don't regret it ONE BIT.
As mentioned, it's really nice to KNOW that you have some "free time" every night to unwind kid free. This is incredibly important for couples. Otherwise, you get away from what brought you together as a couple in the first place, and you never leave "mommy and daddy" mode. Plus, kids need to know (imo) that mommy and daddy need alone time too. I like being able to schedule dates with DH and know that we can be there to put our kids to bed and then go out (don't like the idea of a babysitter giving our kids a bath and putting them to bed...) and they will be asleep the whole time. I like that when I've put in 12 hours as a "mom", I can get a break when it's bedtime. DH is military, and is gone a LOT. I'm essentially a single mom when he's gone, and I am SO tired by 7pm every night that I usually go to bed shortly after them! On those rare nights when one is sick or something, and they are up until 9 or 10...man, those are rough nights!
Now, a feeding schedule, I'll never agree with. My kids still eat when they're hungry. We don't have set eating times. But, bedtime might as well be etched in stone as far as I'm concerned.
Toddlers NEED about 11-14 hours of sleep daily. When those naps go away, all you will have is the nighttime sleep. An earlier bedtime translates to a child who is getting enough sleep, particularly when school starts and the kid has to be up between 6-7am to get to school on time. We are routinely reminded by our kid's school that "Kids need enough sleep to perform well in school." I am guessing that MANY kids come to school and are tired during the day. I bet those kids parents think a "good" bedtime is around 9-10pm, and that's just too late when a kid has to be up at 7...
Take my post for what it's worth. Think about your own life, as well as the lives of other adults you know. EVERYONE (mostly) is on a "schedule". That's the way the world is. You have to be at work at a set time, and work so many hours. When in school, you have to be there on time, and stay until it's over. In college, you have to be at class at a specific time, etc. There are schedules all around you. Allowing your baby to "wing it" is fine when she's a BABY, but eventually, she'll have to adapt to scheduled life. And, it will be much easier on all of you if she is familiar with this concept early on.