Not being a 4e player I'm curious; what about 4e boss fights makes them exciting? Last I heard (before reading this thread), they were considered a slog.
I think the OP is basically talking about 4E's highly detailed dynamic combats, and how they add a huge amount of colour to a combat scene. Typically PCs and monsters are knocked around the board, need to maneuver carefully, and suffer then throw off various short-term disadvantages. You don't necessarily want that detail all the time (or even most of the time). But a climactic combat encounter would be a good point to break them out.
I think the much-trailed tactical combat module will be a big deal towards this. It should hopefully be possible to play a mix of quick TotM mapless encounters and bigger more detailed set pieces. That would definitely suit my group. What would spoil it is needing to build PCs that play well in one or other combat style (e.g. if tactical combat was linked to feats, which would encourage games to either use it all the time or not at all).
Edit: So you could replace "boss battle" in the OP with "final climactic battle" and not get too worried about solos versus other monster types. The point is the 4E includes lots of game elements that mean the tactical skirmish game rarely disappoints (as a skirmish game), but that an unwanted side effect of this is takes so long to play it squeezes out other fun things players like to have in a D&D game.
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