Would it not be more sensible to normally say nothing about the approach, because all pilots will expect an ILS approach anyway (unless it is NOTAMed off)? Then, ONLY if the ILS or glideslope was off; say "Expect a Localiser/VOR/NDB approach"?
The reason it's on is to clearly identify what approach is in use... just because the airport has an ILS doesn't mean it wil be the default approach aid. Can understand where you're coming from but there are a variety of reasons. ILS might be unavailable in the short term, either if u/s or if Tels are doing maintenance on it, and there's been no time to NOTAM it if it's just gone u/s while you're airborne. What if for the same reasons Radar is out of service and so it's Procedural (hence no radar vectors)... the reason it's put on the ATIS, as superfluous as it may initially seem, is to clearly confirm to pilots what approach is in use at the time and what to prepare for. And of course everyone checks the ATIS before they call Radar/Approach first don't they...
Smithy