No default measure for readability.corpus()

[tpaskhalis]

There is currently no default measure when readability function is called on corpus object. I find the behaviour illustrated below rather unintuitive. Are there any downsides in having the same defaults in both cases?

> readability(inaugCorpus)
 Error in match(x, table, nomatch = 0L) : 
  argument "measure" is missing, with no default

> readability(inaugCorpus[c(1,2)])
                     ARI  ARI.NRI ARI.simple    Bormuth Bormuth.GP  Coleman Coleman.C2
1789-Washington 31.65805 26.11026  104.09872 -11.282625 3681191858 43.00944   37.78427
1793-Washington 17.77389 14.54444   76.41667  -6.262506  631167213 41.81667   38.61296
                Coleman.Liau Coleman.Liau.grade Coleman.Liau.short Dale.Chall Dale.Chall.old
1789-Washington     37.51286           12.78528           12.78660  -7.140472      -24.85866
1793-Washington     43.30799           11.19739           11.19852  10.453241      -26.38345
                Dale.Chall.PSK Danielson.Bryan Danielson.Bryan.2 Dickes.Steiwer       DRP
1789-Washington      -24.67452        10.24122          85.47853      -408.2724 1228.2625
1793-Washington      -26.45765         7.44807          84.66330      -111.2295  726.2506
                     ELF Farr.Jenkins.Paterson    Flesch Flesch.PSK Flesch.Kincaid
1789-Washington 21.91667             -93.00380  4.667707   10.05314       27.41044
1793-Washington 12.75000             -66.76818 32.205417    7.97248       17.15176
                meanSentenceLength meanWordSyllables      FOG  FOG.PSK  FOG.NRI  FORCAST
1789-Washington           59.58333          1.674825 31.86131 18.00659 883.0146 10.52797
1793-Washington           33.75000          1.659259 22.09259 11.19467  46.0875 10.66667
                FORCAST.RGL    Fucks Linsear.Write      LIW      nWS    nWS.2    nWS.3    nWS.4
1789-Washington    10.01077 294.7083         7.625 85.80711 15.25046 15.87002 16.18295 19.63952
1793-Washington    10.16333 160.0000         6.750 61.15741 11.30941 11.88745 11.67994 13.16552
                   RIX     SMOG   SMOG.C SMOG.simple  SMOG.de    Spache Spache.old  Strain
1789-Washington 15.625 22.88425 21.92503    21.94070 16.94070 10.953618  12.475774 29.9375
1793-Washington  9.250 18.51114 17.77505    17.74788 12.74788  7.840528   8.846639 16.8000
                Traenkle.Bailer Traenkle.Bailer.2 Wheeler.Smith Scrabble
1789-Washington       -926.5236         -289.4765      219.1667 1.706789
1793-Washington       -592.7418         -265.6644      127.5000 1.721875