Size Current data sets produced by large ground based observational programmes and space missions are very large, conventional means of accessing these data are totally impractical. Cost Space missions and operation of increasingly larger ground based projects are expensive. To avoid monopolies by small groups of individuals, such projects come with limited data rights and provisions for network access. Convenience e.g. Simple access to multiwavelength data on individual objects. Abstracts of journals available 4 weeks before publication.
Increasingly information is only available in electronic format.
Journals are likely to become uneconomical in paper form. Telescopes will increasingly be run remotely. Equally important of course is ensuring that your data, publications etc. etc. are as easily accessible and referable as everyone elses'.