I'll try to explain. Letts suppose we have the following method to fetch data
from the database:

BizEntity[] e = bll.ExecuteQuery("type of the business object", " property
name of the business object", ....);

It takes as first parameter name of the business logic entity which objects
I want to get, and other parameters are names of the properties I want to be
loaded of the fetched objects (suppose we have a delay loaded business
objects).
I can rewrite this snippet:

BizEntity[] e = bll.ExecuteQuery(typeof(BizCustomer), " property name of the
BizCustomer", ....);

Now if for some reason business entity "BizCustomer" will be deleted or
renamed the error will be show at compile time. This is really good ability,
espessially for the large systems with lots of business objects.
Now suppose we have "propertyof" keyword, then the snippet will be like this:

BizEntity[] e = bll.ExecuteQuery(typeof(BizCustomer),
propertyof(BizCustomer.Name), ....);

And the compiler will show us an error even if the property "Name" of the
"BizCustomer" object will be renamed or deleted.

As you see I cannot use reflection because I will need to use string names
of the properties anyway so it will not help.

And I cannot see why Microsoft havn't provided such possibility.