I'm probably in the minority, but I never felt like bringing more children into our family was sad for the older kids. I'm an only child, and I see the benefits of my kids having siblings as endless. Sure, your time with each child will be different, but I think it's better!
I agree with you! Besides I have three with four on the way and I get plenty of alone time with each kid, you just have to find the time. I take my two older ones to basketball each week and we hang out after. My preschooler is home alone with me half days when he get home from pre-k till the older kids get home. Even when they are a little you can get one and one time when the baby naps which is a lot, you can play together. Getting a sitter, or leaving them with dad and taking them somewhere alone. When one or two are doing something else I read on the couch or cuddle with one. We don't always do stuff all together.
The OP read kind of sad, but I just don't really see it that way. There is a bit of a learning curve for the oldest to adjust to a new one, but if you are positive about the change, it helps the tone of the transistion.