I understand your concern. We've had a lot of discussion about whether to abandon the Java style API for one more friendly to .NET, one of the more in depth ones where we seemed to finally come to a consensus was here in this mailing list thread and its history.
Ultimately .NET properties are nothing more than syntactical sugar, since there's no real performance benefit over using a Get/Set method. Either one has just as likely of a change to be inlined than the other. However, it makes Lucene.NET stand out from the rest of the .NET libraries, where .NET features are used (and rightly so).
I'm not sure that deviation from the original API is a valid reason not to implement this feature (not to mention, it's been partially implemented already), considering the plan is and always has been implementing a newer .NET API. There have been considerations to emulate the Java API on top of the new API in the future for people that want that, but IMO it's not really worth it.
Either way, I don't want to get into a discussion about whether to stick to the java API here, that's something for the mailing lists. If you have objections to the ultimate goal of the project, it would be best you voice them on the dev mailing list. I don't think our community is as talkative as it could be, and we only get input from non-committers from just a few vocal community members. We'd love to hear your input on our goals.