Why not rebuild indexes with page count <1000?
The guidance concerning the minimum number of pages is somewhat arbitrary. The biggest benefits of reducing fragmentation are:


It can improve read-ahead performance for large range scans; and
It may improve the page density (number of rows per page)


Both of these factors are less important for small indexes, by definition.

The counter-argument to rebuilding small indexes is essentially:


  "Why bother? Don't you have more important things to worry about?".


That said, rebuilding/reorganizing is not free. It may be worth avoiding the extra effort and log generation in some cases (for example, if the log is shipped/copied across a WAN for any number of possible reasons - mirroring, availability groups, replication...). Also, unless (or even if, in some cases) you are rebuilding online, the rebuild may impact other concurrent processes through locking. Finally, for small indexes, rebuilding may not even reduce the fragmentation anyway, due to allocations from mixed extents (unless you are running with trace flag 1118 enabled).

If you still feel happier rebuilding these small indexes, and don't mind the consequences, then by all means change the value of the @PageCountLevel parameter passed to Ola's procedure.

See the PASS TV recording of Paul Randal's presentation on Index Fragmentation for all the details.

You might also like to watch Brent Ozar talk about Why Index Fragmentation doesn't matter in SQL Server.