Because fundamental investors believe there is a disconnect between price and value. If they are right they should only be disappointing when value drops. When Prices drop and values either stay steady or rise this could be considered positive so long as they weren't planning on liquidating any time soon and have extra capital available - planning/needing to sell in the short/medium term regardless of future valuation and price changes doesn't fit well with fundamental investing it's a recipe for failure really. In the long run if you can stick to your guns and so long as you are better than average at guessing value it all works out when combined with margin of safety (buying below your valuation to skew returns/probabilities in your favour) and sensible allocation strategies (reducing the risk of being wiped out by statistically unlikely events).
You make it sound like bottoming out behavior is obvious yet studies tend to show that traders on average lose LOTS of money so it can't really be that easy at least not for most people. Anecdotally I witness thousands of accounts where this is also true. None of that makes it impossible but clearly you need something that sets you out from the pack along with sound plans for mitigating risks etc
just like fundamental investing.
As for combining both strategies.. well if you can come up with an overall plan that works this way then good for you. Personally I don't entirely ignore charts in my fundamental investing, just 99%
: I do a small amount of trading too btw and the rules I trade by are very different and in some ways opposite to my fundamental investing rules - that doesn't make either of them wrong it depends on how they fit within the overall investment plan. Sometimes you're required to give up a little to gain a lot. I would love to see you sit in front of Buffet and tell him there's these blatant holes in his strategy.