To clarify, the 7-day rail pass costs Y28,300.

If you buy the fares individually, your main costs will be Y3,000 for a NEX ticket, Y13,000 for a Shinkansen ticket from Tokyo to Osaka, and Y1,000 for a ticket from Osaka to KIX (rounded off). A round-trip from Osaka to Kyoto, Kobe or Nara on a regular JR train is just over Y1,000. In the Tokyo area most of your train hops will be in the Y200-Y300 range each way.

So unless you're going somewhere more far-flung in the course of your trip, the rail pass probably won't be cost-effective, and it can also be inconvenient in that it limits you to JR lines.