I posted this long reply on Facebook to someone who was not sure why she had to quilt her quilt tops. The question made me think, and as FB is good at losing stuff, I'll put it here
Quilting does two things, firstly it makes the quilt a quilt - without that stitching all the way through it's something else. Even the simplest quilting adds texture and life and depth to the finished quilt.
Secondly, it's structural.. Many makers think that patchwork is enough, and that's fine, but the end product is neither strong nor will it last if washed and used, nearly as well as if the layers are sewn together all over, as in "quilted". It's all very well wanting a tidy back, but the unsecured lining will flop, handle badly, and may well shrink at an odd rate. The patchwork will not be well-supported by a batting layer only, may pull out of shape, and can end up with open seams. Are your seam allowances perfect? Fine if they are, and not too small, but the 1/4-inches we usually use are a minimum to hold the fabrics together until the piece is stabilised by the quilting.. If you really must make a "duvet cover" or similar, consider a 1/2 inch seam (you'll need to revise the cutting sizes), or overlocking everything, or just hand-washing VERY GENTLY for the life of the item..
When I make a quilt, I like the quilting to work for the look, the structure, and the handle of the finished item. You really don't have to have a batting layer, lots of early quilts are just a top and a back (technically a "coverlet").
You do have to have a really good reason for doing it a different way.
So, if you can't quilt big things, make small ones. Want a bed quilt? Do Quilt-as-you-go if that's what you like. Send it out (think of this as employment for long-armers, not as a "cheat") and be happy with the result (modern long-arm work is pretty spectacular)...
And, meanwhile, practice. Get your machine set up right, on a big table, in a place where you aren't constantly putting it away for meals. Buy a Sew-Ezi or similar so that your machine is at the right height. Get a good walking foot (cheap ones are foul) and make sure it is serviced and oiled occasionally. Take your time..
And, if all else fails, just don't bother to quilt. Make tops and give them away or put them in the cupboard
This is a hobby, not a penance...
Image is Mod Indigo.. Still quilting...