We just observe the fully formed organisms, but the transitionary fossils are all hidden away in niches or never even fossilised.
Well here's a list of 177 transitional fossils:
List of transitional fossils - Wikipedia , so not really all that hidden away.
Also (and I'm turning to the scientists for confirmation here), wouldn't you expect transitional fossils to be rarer ? Simply for the reason that transition will be more common during environmental upheavals or rapid and pronounced environmental change (when selection pressures are stronger) - and since we expect upheavals or periods of change to be fairly short, we equally expect the prevalence of transitional fossils to be lower than fossils laid down during stable periods, when populations are also more stable ?
Could there be any greater conceit, than for someone to believe that the universe has to be simple enough for them to be able to understand it ?