You're right, it's harder to get up to feed than it is to have a baby in bed with you although it's maybe easier to get up and whip out a boob than to prepare a bottle - perhaps only marginally if you use pre-made or whatever I suppose.
Bed sharing with a formula fed baby doesn't help with night feeds although it may help with keeping a baby asleep for longer (or rather, help a baby to settle back to sleep when they wake because they know you are there and they're not alone). I don't like to say "formula feeding parents shouldn't bed share". I prefer to say that formula feeding mothers are less likely to have the same instinct of knowing in her sleep where her baby is than a breastfeeding mother does, so there is a higher risk of a FF mother overlaying her baby than a BFing mother. But who am I to say to an individual mum that she personally should not bed share just because she FFs? She may be super aware of her baby. Over a community fewer FF mums than BFing mums will be, but individuals are individuals.
The advice in the UK is to exclusively breastfeed to 6 months and to look at whether your baby is ready for solids then. Some babies may be ready at 5 or 5 1/2 months. Other not until 7 months, sometimes later. Babies are almost never ready, from a gut maturity point of view, at 4 months, although they may appear to be hungry - more milk is a safer option.
Bed sharing makes breastfeeding (and nights, generally) easier for many people although of course it doesn't suit some. It's perfectly possible to breastfeed to 6 months without bed sharing for many mother/baby dyads, but it can really make it a lot easier for many.
What is perhaps unreasonable is for advice in your country to not be keeping up with the research. However it is the same here in the UK by virtue of the fact that unless Health Visitors go on ongoing training they keep spouting out of date research, and nowadays to go on training they usually have to pay for it themselves and use their own holidays to boot. Now THAT is unreasonable.